Patent Publication Number: US-2012041969-A1

Title: Deriving user characteristics

Description:
BACKGROUND 
     1. Technical Field 
     The present disclosure relates to electronic content delivery and more specifically to intelligent targeting of invitational content to a user based on user characteristics. 
     2. Introduction 
     Targeted content delivery has long been an accepted means of conveying a desired message to an audience. Instead of creating a single message and delivering it to every member of the general public, content providers attempt to identify a particular segment of the population that is likely to have the greatest interest in their message. For example, a content provider might wish to convey a message regarding a service offered in a particular city. To convey this message, the content provider could send out a flyer to all residents of the city. However, if the service is only of interest to residents that own their own home, then targeting all residents of the city is suboptimal for the content provider. Instead, the content provider will attempt to segment the population of city residents into home owners and non-home owners and then only distribute their message to the segment of the population that are home owners. Population segmentation enables content providers to optimize their resources. 
     The development of digital content delivery has enabled new techniques of identifying population segments. For example, segments characterized by mobile device users or users that visit social networking sites. However, these segmentation techniques are often overly simplistic or too broad because they are based on a limited number of user characteristics. 
     SUMMARY 
     Additional features and advantages of the disclosure will be set forth in the description which follows, and in part will be obvious from the description, or can be learned by practice of the herein disclosed principles. The features and advantages of the disclosure can be realized and obtained by means of the instruments and combinations particularly pointed out in the appended claims. These and other features of the disclosure will become more fully apparent from the following description and appended claims, or can be learned by the practice of the principles set forth herein. 
     The present technology provides mechanisms for compiling user characteristics, using those characteristics to associate users with one or more segments of the population, ordering or providing a priority to those segments based on user interest, content provider goals, and/or content delivery system goals, and ultimately delivering targeted invitational content to the user. 
     When a user, or a user&#39;s device, makes a request for targeted content from the content delivery system, the user is sharing some amount of information about him in the request. For example, at a minimum, the user must share some information about the device identification number so that the content delivery system knows which device to send the content back to. Frequently, requests for content can include a much richer collection of data including information about software running on the device, a particular application requesting the content, the connection type of the device, etc. Often a device is associated with an account and in such instances account information is also known and stored as user characteristics. In short, the user shares a good deal of information about him, even if the data isn&#39;t about personal attributes, when he makes a request for data. All of this data can be stored in association with the user as a user characteristic. 
     Further user characteristics can be learned by the content delivery system by mechanisms other than through the actual request for content. In some embodiments, information about a user&#39;s interaction with content, searches conducted by a user, and other usage data can be learned. Additionally, data can be looked up in public databases and associated with a user. For example, if a user&#39;s home address is known, Census data can be used to learn potential demographic information about the user based on the predominate characteristics of the population of people that live in the user&#39;s home town. Again, all of this information can be stored as user characteristics. 
     Knowing characteristics of a user can be valuable in selecting which content is most suitable for delivery to a user. Accordingly, the present technology provides for compiling a collection of user characteristics. Using characteristics that are already known about the user, the present technology can look up additional characteristics or can infer additional characteristics. 
     Of course some user characteristics are considered personal in nature or private and such information should be handled with care. As is discussed in more detail below, such user characteristics are handled only in accordance with applicable laws and governing privacy policies. In many instances, the user is further able to opt-in or opt-out of data collection and/or usage. Further steps can also be taken including deleting user characteristics after they have been used to infer other less personal characteristics or used to select content to be delivered to the user. 
     As addressed above, in some embodiments, user characteristics are inferred from a limited set of known user characteristics. This can be done in a variety of fashions. In some embodiments, a first user can be compared against all other users to find a similar user and user characteristics for the first user can be inferred to be the same as those associated with the similar user. 
     In some embodiments, user characteristics can be inferred using a series of assignment algorithms. In one example, a user&#39;s gender can be inferred from the preferred salutation they use. A user having a salutation of “Mr.” is likely male, and a user having a salutation of “Mrs.” is likely female. Thus gender can be inferred for some users. A variety of other user characteristics can be inferred from the limited set of information already known about the user. 
     Since many user characteristics are being inferred, it is also useful to provide confidence scores to indicate the likelihood that a given user characteristic is correct. For example, in the embodiments where a gender is inferred from a salutation the system might assign a confidence score of 95% because a user&#39;s salutation usually is a good indication of their gender. However, in the embodiments wherein a user&#39;s characteristics are based on other similar users, the confidence score might only be 50%. 
     In instances wherein the confidence score is not sufficient, the system can continue to pursue that user characteristic to gain additional confidence in it. If the system derives the same characteristic values repeatedly, the confidence might be increased. Another way to have greater confidence in an inferred or derived user characteristic is by having a larger sample size. For example, if there are many similar users and they all have the same value for a given characteristic then inferring that the first user has the same characteristic might be likely. 
     Another way of deriving user characteristics is through a user&#39;s products. Products should be broadly thought of as any product or content that a user owns, has previously purchased, is considering purchasing, has viewed in an online store or advertisement, etc. From a collection of products the system can infer many user characteristics. For example, if the user owns an item of digital content targeted at teenagers, the system can infer that the user is a teenager. Of course, inferences made based on one product might have a low confidence score because of the small sample size. One way to increase the sample size is to look more broadly at all the content or, more generally, products that the user owns and infer that the user is a member of the predominate age group for which those products were targeted or intended or purchased. Another way to increase the sample size is to use a similarity algorithm, such as a product similarity software routine to find similar products to one or more products associated with the user. The similarity algorithm can identify other products that co-occur with the first product in other users&#39; purchase histories or content libraries. Accordingly, the collection of similar products will provide a better data set from which to infer a user characteristic, such as age. 
     As will be discussed below, there are many other ways to infer user characteristics. The goal being to derive a complete set of quality user characteristic data. The library of user characteristics is used to identify and place the user into one or more targeted segments, which are associated with content to be delivered to the users in the targeted segments. Accordingly, each user is grouped into one or more targeted segments and, based on the user&#39;s inclusion in those segments, requests for targeted content can be served to the user. The list of targeted segments to which a user belongs is also stored by the content delivery system. 
     The collection of targeted segments to which a user belongs is repeatedly updated. The content delivery system is always learning and user characteristics are always being refined and, in some instances, even changing. Based on the new and additional information the system can recompile or update the list of segments to which a user belongs. 
     In some embodiments, the content delivery system can send an item of targeted invitational content to a user based on the user&#39;s inclusion in a segment. Based on the user&#39;s interaction with the targeted content, and/or one or more other user characteristics, the system can assign the user to a new segment and then target invitational content to the user based on the user&#39;s inclusion in the new segment. 
     While greater detail on individual segments is provided below, a user can be assigned to one or more segments based on demographics, behaviors, inferred interests, progress along a conversion continuum, location, etc. For example, some segments are purely demographic wherein a user is assigned to a segment because the user is of a specified gender and age range—for example, male age 25-39. Segments can be based on inferred interests such as based on the inference that a user is interested in purchasing an automobile based on user characteristics indicating a recent string of searches for automobiles or an increase in time spent viewing automotive related content. Segments can be based on how likely a user is to convert a given item of invitational content based on how much time a user has spent viewing related content or whether the user has clicked on the invitational content in the past. Segments can be based on location such as when user characteristic data indicates a user lives in California, but her current location is New York, the user can be placed into a segment for travelers. Segments can also be assigned based on any blending of user characteristics such as car buyers with the money to purchase a car. 
     Not only can segments be created and assigned by the content delivery system, but in some embodiments content providers can create their own segments. Since the content providers are often creating the content with a specific target audience in mind, the content delivery system provides a user interface to allow the content providers or other users of the system to create custom targeted segments. The system can provide a user interface with all user characteristics collected by the system or all targeted segments available. Using the interface, the content provider can select different user characteristics or segments and mix and match the categories to result in a new segment. The interface also presents all available values associated with a user characteristic category for more refined selection by the content provider. The content provider can select one or more values or ranges of values in creating the custom segment. 
     The interface also allows assignment of weights to be associated with the selected categories to refine the created custom segment. In some embodiments, the system allows a content provider to specify at least one weighting function for causing the content delivery system to provide a differential selection of content associated with a portion of the collection of characteristic values during fulfillment of the booked electronic campaign. 
     In some embodiments, the custom segment is created by selecting a plurality of target users and using characteristics that the target users have in common to define the custom segment. 
     In some embodiments, the system can also save the custom segments for later use by the provider or other providers. 
     In some embodiments, the segments the user is assigned to can be a reflection of a user&#39;s context or mode. A user&#39;s context includes a user&#39;s behavioral patterns, state-of-mind, or interest in one or more topics, content, or products in general. A user&#39;s mode includes a user&#39;s context in a broader sense of any factor relevant to how a user might view or respond to being presented with targeted content. 
     While a user can be assigned to many different segments, the user is likely to be most interested in content that she is presently interested in. While the user might be in a segment for her demographic of female, married, with a child, and accordingly one of her interests is frequently parenting content, today she is planning a vacation so the content that is most suited to the user is vacationing related content. In such an example, the user may have been assigned to segments related to parenting and travel, but the more recent user characteristics suggest that traveling is on her mind. In such an example, both the parenting segment and the travel segment should not be considered equal by the system. Thus the system can prioritize or rank or order segments based on the user&#39;s present interests, contexts, or modes. In such an example, the system selects travel related targeted content to send to the user before, or more often than, parenting content. 
     Just as the system can order the segments according to the user&#39;s context, the system can also order or prioritize or rank segments based on the content provider&#39;s or content delivery system&#39;s goal or priorities. A content provider might desire for its content to be delivered to users in specific segments, or might desire for its content to be viewed by a certain number of users. In some embodiments, the content delivery system can have obligated itself to meet the goals of the content provider. Of course, it can be appreciated that given the limited number of users, and the potentially competing goals or interests of the content delivery system to meet each of its obligations to each of the content providers with the interests of the individual content providers, the prioritization of some targeted segments over others can require optimization to meet the needs of all parties to the system. 
     Accordingly, the content delivery system can monitor its performance in meeting any known goals, and should the content delivery system recognize that its progress towards meeting a goal is not satisfactory, the content delivery system can prioritize some segments over others to meet one or more goals. 
     It should be recognized that reprioritizing a selection of segments can impact other system and content provider goals. Accordingly, the system can also be provided with a performance predictor. The performance predictor is a “what if” scenario engine that can run a series of prediction models to predict the optimum prioritization of segments to result in the best performance of the system. Such a performance predictor can predict performance based on past, observed results from serving similar content in the past. For example, in previous campaigns it can be known that if the system targets a user expected to be looking for a rental car with content related to a first rental car company, that more often than not, the user will not click or convert targeted content related to a second rental car company. Based on such past performance, the system can predict that rearranging the priorities of the system might negatively impact one or more campaigns and look for a different arrangement of priorities to optimize the performance of the system towards meeting all system and provider goals. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In order to describe the manner in which the above-recited and other advantages and features of the disclosure can be obtained, a more particular description of the principles briefly described above will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings. Understanding that these drawings depict only exemplary embodiments of the disclosure and are not therefore to be considered to be limiting of its scope, the principles herein are described and explained with additional specificity and detail through the use of the accompanying drawings in which: 
         FIG. 1  illustrates an exemplary configuration of devices and a network; 
         FIG. 2  illustrates a sampling of events that can be known to the content delivery network; 
         FIG. 3  illustrates a schematic diagram of a user characteristic space; 
         FIGS. 4A-C  illustrate an overview of matching invitational content with users via segmentation; 
         FIG. 5  illustrates an overview of an exemplary user segmentation process; 
         FIG. 6  illustrates an exemplary method embodiment for deriving unknown user characteristics; 
         FIG. 7A  illustrates an exemplary collection of user characteristic values collected from a population of users; 
         FIG. 7B  illustrates an exemplary collection of user characteristic values collected from a population of users with a derived value; 
         FIG. 8  illustrates an exemplary method deriving an unknown gender characteristic; 
         FIG. 9A  illustrates a first exemplary method for inferring the gender characteristic; 
         FIG. 9B  illustrates a second exemplary method for inferring the gender characteristic; 
         FIG. 10  illustrates an exemplary method for deriving a current zip code user characteristic value; 
         FIG. 11  illustrates an exemplary method for deriving a home zip code user characteristic value; 
         FIG. 12  illustrates an exemplary method for deriving a current city user characteristic value; 
         FIG. 13  illustrates an exemplary method for deriving a home city user characteristic value; 
         FIG. 14  illustrates an exemplary method for deriving a current DMA user characteristic value; 
         FIG. 15  illustrates an exemplary method for deriving a home DMA user characteristic value; 
         FIG. 16  illustrates an exemplary method for deriving a country user characteristic value; 
         FIG. 17  illustrates an exemplary method for deriving a current time zone user characteristic value; 
         FIG. 18  illustrates an exemplary method for deriving a home time zone user characteristic value; 
         FIG. 19  illustrates an exemplary method for deriving a date and day part user characteristic value; 
         FIG. 20  illustrates an exemplary method for deriving an age range user characteristic value; 
         FIG. 21  illustrates an exemplary method for deriving life stage and marital status user characteristic values; 
         FIG. 22  illustrates an exemplary method for deriving a life stage user characteristic value; 
         FIG. 23  illustrates an exemplary method for deriving an ethnicity user characteristic value; 
         FIG. 24  illustrates an exemplary method for deriving an income user characteristic value; 
         FIG. 25  illustrates an exemplary method for deriving a preferred purchase category user characteristic value; 
         FIG. 26  illustrates an exemplary method for deriving a spend level user characteristic value; 
         FIG. 27  illustrates an exemplary method for deriving a purchase frequency user characteristic value; 
         FIG. 28  illustrates an exemplary method for deriving a work-home-commute user characteristic value; 
         FIG. 29  illustrates an exemplary method embodiment for generating a custom targeted segment; 
         FIG. 30  illustrates an exemplary graphical user interface for creating a custom targeted segment; 
         FIG. 31  illustrates an exemplary method embodiment for selecting invitational content to send to the user based on demographic segmentation; 
         FIG. 32  illustrates an exemplary method embodiment for selecting invitational content to send to the user based on behavioral segmentation; 
         FIG. 33  illustrates an exemplary method embodiment for prioritizing targeted segments associated with a user; 
         FIG. 34  illustrates an exemplary segment assignment prioritization process; and 
         FIG. 35  illustrates an example system embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Various embodiments of the disclosure are discussed in detail below. While specific implementations are discussed, it should be understood that this is done for illustration purposes only. A person skilled in the relevant art will recognize that other components and configurations may be used without parting from the spirit and scope of the disclosure. The present disclosure addresses the need in the art for improved methods of selecting targeted content presented to a user based on characteristics descriptive of the user and/or the user&#39;s interaction with one or more items of targeted content. 
     The presently disclosed system and method is particularly useful for matching targeted content with a user in a manner that leads to a higher probability of conversion. An exemplary system configuration  100  is illustrated in  FIG. 1  wherein electronic devices communicate via a network for purposes of exchanging content and other data. The system can be configured for use on a local area network such as that illustrated in  FIG. 1 . However, the present principles are applicable to a wide variety of network configurations that facilitate the intercommunication of electronic devices. For example, each of the components of system  100  in  FIG. 1  can be implemented in a localized or distributed fashion in a network. 
     In system  100 , content packages are delivered to user terminals  102   1  . . .  102   n  (collectively “ 102 ”) connected to a network  104  by direct and/or indirect communications with a content delivery system  106 . In particular, the content delivery system  106  receives a request for an electronic content, such as a web page, an application, or media, etc., from one of user terminals  102 . Thereafter, the content delivery system  106  assembles the content package in response to the request and transmits the assembled content package to the requesting one of user terminals  102 . In some embodiments, the server has preselected the content package before the request is received. The assembled content package can include text, graphics, audio, video, executable code or any combination thereof. Further, the assembled content packages can include invitational content designed to inform or elicit a pre-defined response from the user and content that can vary over time. For example, the assembled content package can include one or more types of advertisements from one or more advertisers. The content delivery system can include a communications interface  107  to facilitate communications with the user terminals  102  and any other components familiar to those of ordinary skill in the art. 
     The content delivery system  106  includes a content management module  108  that facilitates generation of the assembled content package, which can include invitational content. Specifically, the content management module can combine content from one or more primary content providers  109   1  . . .  109   n  (collectively “ 109 ”) and content from one or more secondary content providers  110   1  . . .  110   n  (collectively “ 110 ”) to generate the assembled content package for the user terminals  102 . For example, in the case of a web page being delivered to a requesting one of user terminals  102 , the content management module  108  can assemble a content package by requesting the data for the web page from one of the primary content providers  109  maintaining the web page. For the invitational content on the web page provided by the secondary content providers  110 , the content management module  108  can request the appropriate data according to the arrangement between the primary and secondary content providers  109  and  110 . 
     Although, primary and secondary providers  109  and  110  are presented herein as separate entities, this is for illustrative purposes only. In some cases, the primary and secondary providers  109  and  110  can be the same entity. Thus, a single entity can define and provide both the primary and the secondary content. 
     Although the content management module  108  can be configured to request that content be sent directly from content providers  109  and  110 , a cached arrangement can also be used to improve performance of the content delivery system  106  and improve overall user experience. That is, the content delivery system  106  can include a content database  112  for locally storing/caching content maintained by content providers  109  and  110 . The data in the content database  112  can be refreshed or updated on a regular basis to ensure that the content in the database  112  is up to date at the time of a request from a user terminal. However, in some cases, the content management module  108  can be configured to retrieve content directly from content providers  109  and  110  if the metadata associated with the data in content database  112  appears to be outdated or corrupted. 
     In the various embodiments, the content delivery system  106  can also include a unique user identifier (UUID) database  116  that can be used for managing sessions with the various user terminal devices  102 . The UUID database  116  can be used with a variety of session management techniques. For example, the content delivery system  106  can implement an HTTP cookie or any other conventional session management method (e.g., IP address tracking, URL query strings, hidden form fields, window name tracking, authentication methods, and local shared objects) for user terminals  102  connected to content delivery system  106  via a substantially persistent network session. However, other methods can be used as well. For example, in the case of handheld communications devices, e.g. mobile phones, smart phones, tablets, or other types of user terminals connecting using multiple or non-persistent network sessions, multiple requests for content from such devices may be assigned to a same entry in the UUID database  116 . The delivery system  106  can analyze the attributes of requesting devices to determine whether such requests can be attributed to the same device. Such attributes can include device or group-specific attributes. 
     As described above, content maintained by the content providers  109  and  110  can be combined according to a predefined arrangement between the two content providers, which can be embodied as a set of rules. In an arrangement where the content delivery system assembles the content package from multiple content providers, these rules can be stored in a rules database  118  in content delivery system  106 . The content management module  108  can be configured to assemble the content package for user terminals  102  based on these rules. The rules specify how to select content from secondary content providers  110  and primary content providers  109  in response to a request from one of user terminals  102 . For example, in the case of a web page maintained by one of primary content providers  109  and including variable advertisement portions, the rules database  118  can specify rules for selecting one of the secondary providers  110 . The rules can also specify how to select specific content from the selected one of secondary providers  110  to be combined with the content provided by one of primary providers  109 . Once assembled, the assembled content package can be sent to a requesting one of user terminals  102 . However, the content package is not limited to the content from content providers  109  and  110 . Rather, the content package can include other data generated at the content delivery systems  106 . 
     One concern with the arrangement typically entered into by secondary content providers  110  is that they can result in invitational content of little or no interest being presented to users. As a result, even though a desired number of impressions can be achieved, the rate of response to such invitational content may be low and/or the resulting targeted audience may be incorrect or suboptimal. Additionally, in most content delivery environments, such as that of system  100 , the number and type of providers  109  and  110  are generally not static. For example, the number of primary content providers  109  and the amount and type of space they provide for secondary content providers  110  can vary over time. Further, the number of secondary content providers  110  can vary over time, as well as the amount and types of space they require from primary content providers  109 . Further, the types of users and user terminals of interest to the secondary content providers  110  can also vary over time. As a result, selecting optimal invitational content to present to a user can quickly become complicated in such a dynamic environment. 
     The various embodiments disclosed herein provide systems and methods for intelligently targeting invitational content to a user based on user characteristics. A first aspect of the present technology provides systems and methods for deriving uncertain user characteristics based on known data. A second aspect of the present technology provides systems and methods for generating a custom targeted segment. A third aspect of the present technology provides systems and methods for assigning a user to one or more demographic segments. A fourth aspect of the present technology provides systems and methods for assigning a user to one or more behavioral segments. A fifth aspect of the present technology provides systems and methods for prioritizing targeted segments associated with a user. 
     As used herein, the term “user characteristics” refers to the characteristics of a particular user associated with one or more of user terminals  102 . User characteristics can include channel characteristics, demographic characteristics, behavioral characteristics, and spatial-temporal characteristics. Channel characteristics can define the specific delivery channel being used to deliver a content package to a user. For example, channel characteristics can include a type of electronic content, a type of device or user terminal, a carrier or network provider, or any other characteristic that defines a specific delivery channel for the content package. Spatial-temporal characteristics can define a location, a date, a time, or any other characteristic that defines a geographic location and/or a time for delivery of the content package. Demographic characteristics can define characteristics of the users targeted by the content or associated with the content. For example, demographic characteristics can include age, income, ethnicity, gender, occupation, or any other user characteristics. Behavioral characteristics can define user behaviors for one or more different types of content, separately or in combination with any other user characteristics. That is, different behavioral characteristics may be associated with different channel, demographic, or spatial-temporal characteristics. User characteristics can also include characteristics descriptive of a user&#39;s state of mind including characteristics indicative of how likely a user is to click on or convert an item of invitational content if it were displayed to the user. 
     User characteristics can be learned directly or derived indirectly from a variety of sources. For example, the graph  200  in  FIG. 2  illustrates a sampling of events from which the delivery system  106  can directly learn user characteristics and/or derive other user characteristics. Even though  FIG. 2  illustrates a fair number of events as data sources, the figure should not be considered limiting. As will become apparent from the rest of this disclosure, the delivery system can learn of or derive user characteristics from any number of other information sources. 
     In some embodiments, the invitational content provided by the secondary content providers  110  is associated with one or more targeted segments. A targeted segment can be viewed as defining a space or region in k-dimensional space, where each of the k dimensions is associated with one of a plurality of user characteristics. This is conceptually illustrated in  FIG. 3 . In the various embodiments, the k dimensions can include both orthogonal and non-orthogonal dimensions. That is, some of the k dimensions can overlap or can be related in some aspect. For example, if separate dimensions are specified for city and state, these dimensions are non-orthogonal. 
       FIG. 3  is a schematic diagram of a user characteristics space  300 . As shown in  FIG. 3 , the space  300  is defined by demographic characteristics, specifically age, income, and ethnicity. Each targeted segment in space  300  is associated with one or more user characteristics. A content provider wishing to present an item of invitational content to Spanish users aged between 18 and 20 and having an income between $50,000 and $70,000, would associate the invitational content with a targeted segment defined by those characteristics and values. However, a broader targeted segment could also be associated with the item, such as a targeted segment defined by the user characteristic age and the value 18 to 20. Although, the space  300  in  FIG. 3  is defined in terms of a few demographic user characteristics, other user characteristics can also be used, such as channel, behavioral, and spatial-temporal characteristics described herein. 
     Referring back to  FIG. 1 , in some embodiments, the content delivery system  106  can include a user-profile database  120 . The user-profile database  120  can, at least in part, be constructed based on recorded user characteristics related to one or more users. In some cases, the user-profile database may contain uncertain or incomplete user characteristic values. 
     The user-profile database  120  can be updated using a user-profile-updater module  122 . In some embodiments, the user-profile-updater module  122  can be configured to add additional profile data, update profile data, fill in missing profile data, or derive uncertain user characteristic values from trusted data. A method of deriving uncertain user characteristics based on trusted data is described in greater detail in  FIG. 6  below. 
     The updater module  122  can also be configured to maintain the profile database  120  to include only more recently acquired data or to re-derive any uncertain characteristics in order to ensure that the user profile is an accurate reflection of the current state of the user (location, state of mind, behaviors, demographics, etc. can change rapidly). For example, the updater module  122  can be configured to maintain the profile database  120  to include only data from the last two to three months. However, the updater module  122  can be configured to adjust the data in profile database  120  to cover any span of time. In some instances the updater module  122  can update the profile database  120  in real-time. In some instances, the updater module  122  can update the profile database  120  at least every week, or every day. In some cases, the delivery system  106  can receive a direct request to update one or more user profiles. The update request can come directly from the user&#39;s device or any other device capable of communicating with the delivery system  106 , such as other content delivery networks or websites. In some cases, the delivery system  106  can receive an indirect request to update one or more user profiles. An indirect request can be the result of receiving new user characteristic values. An update request can occur at any time. 
     In some embodiments, the content delivery system  106  can include a segment database  114  that is used to aid in selecting invitational content to target to users. The segment database  114  stores defined segments and associations between the segments and users and/or invitational content that should be targeted to users associated with the segments. As described above, a targeted segment can be defined based on one or more user characteristics or derivatives thereof and can be associated with one or more items of invitational content. Additionally, a targeted segment can be associated with one or more users. In some embodiments, by associating a targeted segment with both a user and an item of invitational content, the delivery system can match invitational content with users. In some embodiments, the delivery system  106  can update the segment database  114  to add newly defined targeted segments or to delete targeted segments. 
     In some cases a targeted segment can be as simple as a single user characteristic identifier and a single user characteristic value. For example, the common demographic identifiers of gender, age, ethnicity, or income can each be used in defining corresponding targeted segments. A characteristic value can also be assigned to the identifier. For example, the values of male, 19, Indian, and $20,000-$30,000 can be assigned to the user characteristics of gender, age, ethnicity, and income, respectively. However, more complex targeted segments can also be defined that consist of one or more identifiers with one or more values associated with each identifier. For example, a targeted segment can be defined to target a user with the following characteristics: gender, male; age, 19-24; location, Northern California but not San Francisco. Additional exemplary segments are described throughout this disclosure. Furthermore, targeted segments can correspond to one or more segments that content providers are likely to easily understand and thus can quickly identify as being relevant to their content. Additionally, in some embodiments, content providers  109  and  110  can define a custom targeted segment. 
     In some embodiments, the delivery system  106  can include a custom segment creator module  126 . A content provider  109  and  110  can interact either directly or indirectly with the creator module  126  to define a custom targeted segment. A custom segment can be defined based on one or more user characteristics known to the delivery system  106 . In some cases, a custom targeted segment can be saved to the segment database  114  to use later in selecting invitational content. Alternatively, the custom targeted segment can be used immediately to identify invitational content with or without saving the segment to the segment database  114 . An example for custom segment generation is described in greater detail below and in  FIG. 29 . 
     In some embodiments, the content delivery system  106  can provide a segment assigner module  124 . The segment assigner module  124  can apply a set of user characteristics associated with a user (including segments to which a user has been previously assigned) to assign the user to one or more targeted segments. The assigner module  124  can obtain the set of user characteristic values from the user profile database  120  and/or from the user&#39;s activities during the current session. The segment assigner module  124  can assign a user to one or more defined targeted segments in the segment database  114 , or alternatively, a user can be assigned to a custom targeted segment defined to meet specific goals of a content provider. 
     Based on the assigned segments, the user profile database  120  can be updated to reflect the segment assignments. Additionally, the delivery system  106  can use the segment assignments to select targeted content. In some cases, the user profile data in the user profile database  120  can change over time so the segment assigner module  124  can be configured to periodically update the segment assignments in the user profile database  120 . The segment assignment update can be triggered at specified intervals, upon detection of a change in the user profile database  120 , and/or upon detection of a specified activity in the delivery system  106 . 
       FIGS. 4A-C  are collectively an overview of assigned segments that can be used to select targeted invitational content to be presented to a user and a process of refining the segment assignments for the user based on additional information and user characteristics learned as the user interacts with or fails to interact with invitational content presented to him along the conversion process. As a user interacts with content over one or more sessions, the delivery system  106  begins to gain additional knowledge about the user. This knowledge is enhanced when the user completes certain actions, such as clicking or not clicking on a link and/or completing a conversion. This information can then be used to assign the user to one or more targeted segments, such as Affluent Auto Intender, High Converting Device, 10 Mile Commuter, Biz Traveler, etc. Using the targeted segments, content providers can target invitational content that is likely to be of greater interest to the user. Methods for segment assignments are described in greater detail below. 
     In some embodiments, the content delivery system  106  can provide a segment-prioritizing module  128  for ordering the targeted segments assigned to a user. The prioritization can be influenced by a number of factors, which include the user&#39;s context (state of mind of a user with respect to interest in certain types of content, subject matter of content, progress along a conversion continuum, etc.), a content provider&#39;s campaign goals, and/or content that is currently available for display to the user. A request to prioritize the targeted segments can be made explicitly or implicitly by any component in the system  100 . For example, a secondary content provider  110  can explicitly request that the content delivery system  106  prioritize the targeted segments or the request can be implicit as part of a request for an assembled content package. The resulting prioritized list can be provided, for example, to the content management module  108 , which can then use the information to assemble and deliver a content package. Additionally, the prioritized list can be stored, for example in the user profile, for later use. A method of prioritizing targeted segments is described in greater detail. 
       FIG. 5  is an overview of an exemplary user segmentation process  500 . The delivery system  106  starts with a variety of user characteristics. Based on these characteristics, a segment generator  502 , such as the segment assigner module  124 , can assign the user to a variety of segments, such as the mobile discovery segments  510 , mobile relevance segments  520 , and traditional segments  530 . An optimal segment allocator  504 , such as the segment prioritizing module  128 , can order the segments assigned to the user so that segments that are more relevant to the user&#39;s current context are at the top of the list. The delivery system  106  can also include module(s) that carry out the tasks of a performance predictor and optimizer  506 . Such module(s) can further prioritize the assigned segments by predicting user behavior and/or prioritize segments based on campaign goals and/or context. Furthermore, the delivery system  106  can include a custom segment creator  508 , such as the custom segment creator module  126 , which allows content providers to create custom segments. 
     In the various embodiments, the one or more databases described herein can be implemented using any type of data structures. Such data structures include, but are not limited to, data structures for relational databases, key/value stores, graph databases, hierarchical databases, and distributed or columnar stores. Accordingly, although the various embodiments described herein may refer to specific data structures, in other embodiments such data structures can be substituted for any other type of data structure. 
     As described above, one aspect of the present technology is the gathering and use of data available from various sources to improve the delivery to users of invitational content or any other content that may be of interest to them. The present disclosure contemplates that in some instances, this gathered data may include personal information data that uniquely identifies or can be used to contact or locate a specific person. Such personal information data can include demographic data, location-based data, telephone numbers, email addresses, twitter ID&#39;s, home addresses, or any other identifying information. 
     The present disclosure recognizes that the use of such personal information data in the present technology can be used to the benefit of users. For example, the personal information data can be used to better understand user behavior, facilitate and measure the effectiveness of advertisements, applications, and delivered content. Accordingly, use of such personal information data enables calculated control of the delivered content. For example, the system can reduce the number of times a user receives a given ad or other content and can thereby select and deliver content that is more meaningful to users. Such changes in system behavior improve the user experience. Further, other uses for personal information data that benefit the user are also contemplated by the present disclosure. 
     The present disclosure further contemplates that the entities responsible for the collection, analysis, disclosure, transfer, storage, or other use of such personal information data will comply with well-established privacy policies and/or privacy practices. In particular, such entities should implement and consistently use privacy policies and practices that are generally recognized as meeting or exceeding industry or governmental requirements for maintaining personal information data private and secure. For example, personal information from users should be collected for legitimate and reasonable uses of the entity and not shared or sold outside of those legitimate uses. Further, such collection should occur only after receiving the informed consent of the users. Additionally, such entities would take any needed steps for safeguarding and securing access to such personal information data and ensuring that others with access to the personal information data adhere to their privacy policies and procedures. Further, such entities can subject themselves to evaluation by third parties to certify their adherence to widely accepted privacy policies and practices. 
     Despite the foregoing, the present disclosure also contemplates embodiments in which users selectively block the use of, or access to, personal information data. That is, the present disclosure contemplates that hardware and/or software elements can be provided to prevent or block access to such personal information data. For example, in the case of advertisement delivery services, the present technology can be configured to allow users to select to “opt in” or “opt out” of participation in the collection of personal information data during registration for services. In another example, users can select not to provide location information for targeted content delivery services. In yet another example, users can configure their devices or user terminals to prevent storage or use of cookies and other objects from which personal information data can be discerned. The present disclosure also contemplates that other methods or technologies may exist for blocking access to their personal information data. 
     Therefore, although the present disclosure broadly covers use of personal information data to implement one or more various disclosed embodiments, the present disclosure also contemplates that the various embodiments can also be implemented without the need for accessing such personal information data. That is, the various embodiments of the present technology are not rendered inoperable due to the lack of all or a portion of such personal information data. For example, content can be selected and delivered to users by inferring preferences based on non-personal information data or a bare minimum amount of personal information, such as the content being requested by the device associated with a user, other non-personal information available to the content delivery services, or publically available information. 
     The information gathered about a user, whether public or private can be used directly or indirectly to create the UUID database  116 . In many of the embodiments discussed herein, a user is first identified in the UUID database  116  to retrieve, update or write data associated with the user in the UUID database  116 . 
     Identification of the same user in the UUID database can be performed in a variety of ways and the methods employed to identify the user can vary depending on the user&#39;s connection type. In one example of identifying a user in the UUID database  116 , when the delivery system  106  receives a request for a content package, the request can include some identifying information associated with the requesting user terminal or the associated user. This information can then be correlated to an entry in the UUID database  116  to retrieve an identity of the user. In other configurations, the delivery system  106  can analyze the attributes of the requesting device to determine whether such requests can be attributed to a same device. In some embodiments, a user&#39;s behavior in visiting the same content channels can be used to identify the user. Of course combinations of the methods for identifying a user on one or more connection types can be used. 
     As mentioned above a set of user characteristic values can also be associated with a user in the UUID database  116 . In some embodiments, the set of user characteristic values are descriptive of the user. For example, the characteristic values could be demographic characteristics, such as gender, age, ethnicity, and/or income. In some embodiments, the set of user characteristic values are descriptive of the user&#39;s interaction with one or more items of content within a network of targeted content delivery channels. For example, the characteristic values can include details of the user&#39;s conversion history with respect to previously presented invitational content. The conversion history can be limited to whether or not the user converted or could be more detailed to include where on the conversion continuum the user abandoned the process, details about the invitational content presented, and/or where or when the invitational content was presented. The collected values can further include the channel, the device the user was using, the time of day, and/or day of week. In general, the values can be descriptive of any characteristics associated with the user and the user&#39;s actions such as channel, demographic, behavioral, and/or spatial-temporal characteristics. The more extensive the data set the more effective the targeting. 
     In some embodiments, the user characteristic values can be collected from one or more databases. For example, if the user is registered with an online media service, such as the ITUNES store maintained by Apple Inc. of Cupertino, Calif., the collected data could include the user&#39;s registration information and purchase history within the different categories of available media. Possible purchase history characteristics include, but are not limited to, preferred purchase categories, spend level, and recent purchase frequency. Each of these characteristics can be further specialized so as to apply to the various types of media available, such as apps, music, movies, television shows, and books. Some of the purchase history characteristics, as well as other user characteristics in general, can be relative to other users. For example, spend level can be based on a predefined scale or it can be based on the user&#39;s spending habits in relation other users, e.g. the user could be a high, average, or low spender. 
     In some embodiments, the delivery system  106  can determine user characteristic values associated with user characteristics that are pre-defined in the delivery system  106 . For example, age is a possible user characteristic that might be pre-defined in the delivery system  106 . A particular age, such as 19, is a user characteristic value that the delivery system  106  can collect and associate with the age user characteristic. 
     In some embodiments, the delivery system  106  is configured to derive uncertain user characteristics.  FIG. 6  is a flowchart illustrating steps in an exemplary method  600  for deriving uncertain user characteristics associated with a user. For the sake of clarity, this method is discussed in terms of an exemplary system such as is shown in  FIG. 1 . Although specific steps are shown in  FIG. 6 , in other embodiments a method can have more or less steps than shown. 
     Periodically, the content delivery system  106  determines one or more characteristics of at least one product associated with an identified user ( 602 ). A product associated with the identified user can include products that the user has viewed in an online store, products that a user has purchased from an online store, products that are in a user&#39;s multimedia library, etc. Even products that are known to have been advertised to the user can be considered a product associated with the user. The characteristics of a product are similarly wide ranging. They can include demographics commonly associated with the products such as age range of targeted or typical purchasers, content category, genre (if applicable), product type, product color, size, etc. 
     From the product characteristics, user characteristics can be inferred ( 604 ). For example, a user&#39;s age range can be inferred based on the targeted demographic of the product, or from the known ages of other users that bought the same products. A user&#39;s interest in music, or type of music and movies, can also be inferred from the product characteristics. More generally, the type of products that the user is interested in can also be inferred. 
     Based on the characteristics inferred from the product characteristics, the delivery system  106  selects invitational content to send to the identified user from a selection of invitational content configured for target users associated with at least a portion of the inferred characteristic values ( 606 ). In some embodiments, the user characteristics are first used to categorize a user into one or more targeted segments and invitational content is then delivered to the user based on their inclusion in the targeted segments. 
     In some embodiments, inferring data from products associated with the user might not be possible or at least not useful because only a small number of products are associated with the user. In such instances, it can be helpful to use a similarity algorithm to identify additional products that are similar to the few that are directly associated with the user. By using the similarity algorithm, the sample size can be increased and the data derived therefrom is more likely to be reliable. Accordingly, a benefit of the similarity algorithm is that it can result in an increased confidence score associated with the derived value. 
     In a similar fashion to that explained above, user characteristics can be derived or inferred from many sources of data. In some embodiments, the delivery system  106  infers one or more uncertain user characteristic values by comparing one or more trusted user characteristic values with a database of data and then inferring the one or more uncertain user characteristic values from the comparison. Whether the delivery system  106  considers a value trusted can vary depending on the configuration of the system. For example, in some cases any value can be considered trusted. However, in other cases, the delivery system  106  may only trust values that have an associated confidence score greater than a specified threshold value. In some configurations, the delivery system  106  can detect that certain values may not be completely accurate. For example, the delivery system  106  may be able to detect that a user has entered a business address for their home address and thus not consider it a trusted value for the purpose of deriving other user characteristic values. For example, a user may enter a home address of 1 Infinite Loop, Cupertino, Calif. 95014, which is known to be a commercial address. 
     Comparison data can be obtained from any type of database such a public database, like the U.S. Census database, or a private third party database that is accessible to the delivery system  106  or has been incorporated into the delivery system  106 . To illustrate, if one of the trusted characteristics is the user&#39;s address, which was obtained from the user&#39;s registration information, then the delivery system  106  can compare that address with the U.S. Census data to infer the user&#39;s estimated income, ethnicity, gender, religion inter alia. A confidence score can also be assigned to the inferred values. For example, if in a particular town identified in the Census data, eighty percent of the people living in that town fall into the same income range, then the system can infer that it is eighty percent likely that a user in that town falls into that income range and thus, have an eighty percent confidence in the inferred value being accurate. 
     In some embodiments, the delivery system  106  infers one or more uncertain user characteristic values by comparing the set of user characteristic values with a collection of user characteristic values collected from a population of users. In some configurations, the delivery system  106  can obtain the collection of user characteristic values for the population of users from the user profile database  120 . 
     To illustrate a method of deriving an uncertain user characteristic value from a collection of user characteristic values collected from a population of users, consider the table  700  in  FIG. 7A . The table  700  represents a collection of user characteristic values. Each of the users in the table  700  has at least one uncertain characteristic value. That is, each user is missing a characteristic value. In this example, the delivery system  106  is attempting to derive one or more uncertain characteristic values for the user with UUID  3 , so the system compares user  3  with the other three users. 
     From the comparison, the delivery system  106  can identify another user among the population of users with user characteristic values similar to the user. Another user among the population of users can be identified in a number of different ways. In some embodiments, the delivery system  106  can represent the user and each user in the population of users as a vector. Then the delivery system  106  can compute the angle between the vector associated with the user and the vectors associated with each user in the population of users. The delivery system  106  selects one or more users in the population of users in which the computed angle is less than a threshold value and can infer missing values in the user&#39;s profile from the similar user in the population. 
     In some embodiments, the delivery system  106  can construct a “model” user from a population of users. The “model” user can be constructed by averaging the user characteristic values of a population of users. In some configurations, other methods of combining the user characteristic values of a population of users can be used. The delivery system  106  can then use the “model” user as a basis for inferring uncertain user characteristic values for the user. 
     In some embodiments, the delivery system  106  can identify another user among the population of users by computing an overall similarity value. For each pairing of the user and another user in the population of users, the delivery system  106  first computes a similarity value for each user characteristic. For example, consider the user characteristic age. If the user has an age characteristic value of 19 and another user has the same age user characteristic, then the delivery system  106  can assign a similarity value of 1 for the age user characteristic. However, if the another user has an age user characteristic value of 21, then the delivery system  106  can assign a similarity value that is less than or equal to 1. In some configurations, the delivery system  106  can assign a similarity value of 1 because the user and the another user are in the same age range, e.g. 19-24. However, the delivery system  106  can assign a value less than 1 even though the user&#39;s age user characteristic value and the another user&#39;s age user characteristic value are in the same range. Other methods of computing the similarity between two values for a particular user characteristic value are possible. In some configurations, a different method of computing similarity can be used for each user characteristic value. The delivery system  106  is not limited to a similarity value scale of 0 to 1, other scales are also possible, e.g. 0-100. 
     The delivery system  106  then combines the similarity values for the individual user characteristic values to create an overall similarity value for the pairing of the user and the another user in the population of users. For example, the overall similarity value can be computed by averaging the individual user characteristic similarity values for the pairing of the user and the another user. In some embodiments, the similarity value for an individual user characteristic can be weighted to give it a greater or lesser impact on the overall similarity value. In some embodiments, the delivery system  106  uses a subset of the user characteristic values to compute the similarity between the user and other users in the population. Finally, the delivery system  106  selects one or more users in the population of users in which the overall similarity for the pairing is greater than a threshold value and infers additional user characteristic values for the user from values associated with the one or more users in the population of users. 
     Returning to the example based on table  700  in  FIG. 7A , the delivery system  106  determines that User  3  exhibits a sufficient similarity to the users with UUID  1  and  4 . User  1  is selected because all four of User  3 &#39;s trusted user characteristic values are an exact match with user characteristic values associated with User  1 , i.e. Gender, Age Range, Movie Category Purchase History, and App Category Purchase History. User  4  is selected even though only three of his user characteristic values match with User  3 , i.e. Gender, Age Range, and Movie Category Purchase History. The 75% match was a sufficient level of similarity for the configuration of the system. In this case, the delivery system  106  is configured such that trusted simply means characteristic values exist. 
     Then the delivery system  106  infers the one or more unknown characteristic values about the user from the another user with contextual characteristic values similar to the user. Based on the table  700 , user  3  is missing contextual characteristic information for two characteristics: Music Category Purchase History and TV Category Purchase History. In this case, because User  1  and User  4  have differing values for the Music Category Purchase History characteristic, the delivery system  106  is unable to infer a value for User  3  for this characteristic. In some configurations, the delivery system  106  can infer the Music Category Purchase History characteristic from User  1  because User  3  exhibits a greater degree of similarity with User  1 . 
     The delivery system  106  is able to infer a value for the TV Category Purchase History. Based on the characteristics of the similar users, the delivery system  106  infers that User  3  is likely to be interested in the Action &amp; Adventure TV Category. This is reflected in the updated collection of user characteristic values in table  750  in  FIG. 7B . 
     In some embodiments, the delivery system  106  infers the one or more uncertain user characteristic values by inferring the one or more uncertain characteristic values from the set of user characteristic values. There are some user characteristics that the delivery system  106  can infer simply based on other user characteristics known about the user. For example, gender, age, and life stage are illustrative user characteristics that can, in some cases, be inferred from other characteristics known about the user. As an illustration, if one of the known characteristics is the user&#39;s preferred salutation, then it may be possible to infer the user&#39;s gender. In the case where the preferred salutation is insufficient to make a determination, such as when the preferred salutation is Dr., then the delivery system  106  can attempt to infer the gender from other user characteristics such as the user&#39;s purchase history. For example, if the user&#39;s purchase history skews towards categories that are traditionally associated with one gender or the other, then the delivery system  106 , knowing this information, can infer the user&#39;s gender. A method for inferring a gender characteristic value is described in greater detail below in  FIG. 8 . Similarly, purchase history can be used to infer both age and life stage characteristics. For example, if the user&#39;s purchase history contains a mix of children and adult categories, the delivery system  106  may be able to infer that the user&#39;s life stage is that of a parent. Methods for inferring age and life stage characteristic values are described in greater detail below in  FIG. 21-23 . 
     In some embodiments, the delivery system  106  assigns a confidence score to the values in the set of user characteristic values, where the confidence score represents the likelihood that the particular characteristic value is valid and/or correct for the user. For example, a characteristic can be assigned a value in the range [0,1], where 0 indicates no confidence and 1 indicates full confidence. Other relative indicators of confidence can also be used such as a percentage. 
     The calculation of a confidence score can depend on a variety of factors. In some configurations, the user characteristic and/or how the characteristic is obtained can be a factor in the confidence score. For example, a different method may be used to calculate a confidence score for a demographic characteristic versus a behavioral characteristic. Furthermore, if there is more than one method to derive a particular characteristic value, as is illustrated with the life stage characteristic in  FIGS. 21 and 22  below, there can be different methods of calculating the associated confidence score. In some cases, the confidence score can be related to the number of characteristics considered in deriving the value. The confidence score can also be related to the strength of the inference used in deriving a new user characteristic. In the case where the derived value is based on a collection of characteristic values from a population of users or products, the number (sample size) of users in the population or products can also factor into the confidence score. In some embodiments, if the confidence score for a characteristic value is less than a specified threshold value, then the system  106  can, at some point, attempt to re-derive the value to improve the confidence score. Values that are affirmed by multiple methods of attempts to derive a characteristic can likewise be given a higher confidence score. 
     To illustrate one method of calculating a confidence score, suppose the characteristic is content-driven, e.g. extracted from the content using text mining. First, the characteristic value is assigned a score based on the frequency of the value within the content relative to the inverse of the frequency of the value within all content known to the delivery system  106 . Then the score is updated to reflect how the value applies to the particular user. For example, the score can be updated based on how often the user actually interacts with the content. This score can be called a relevancy score. Finally, the relevancy score gets converted into the confidence score based on how well the value applies to the user given the context. 
     In some cases, deriving an uncertain user characteristic value can require using one or more derivation methods to arrive at a trusted value. For example,  FIG. 8  illustrates a full process for deriving a gender characteristic value. The derivation method  800  begins at  802 , where the delivery system  106  fetches the user&#39;s preferred salutation from the account database  804 . The salutation characteristic could have been collected from another database, such as the ITUNES database maintained by Apple Inc. of Cupertino, Calif., which stores the user&#39;s account information. The delivery system  106  then attempts to infer the user&#39;s gender from the fetched salutation ( 806 ).  FIG. 9A  illustrates a method  900  that can be used to infer gender from the preferred salutation. First, the delivery system  106  checks if the salutation is Mr. ( 902 ). If so, the delivery system  106  assigns male to the gender characteristic ( 904 ) and assigns a confidence score of 1 ( 910 ), where the confidence score ranges from 0 to 1 and 1 indicates full or nearly full confidence. If the salutation is not Mr., then the delivery system  106  checks if the salutation is Ms. or Mrs. ( 906 ). If so, the delivery system  106  assigns female to the gender characteristic ( 908 ) and assigns a confidence score of 1 ( 910 ). If the salutation is not Mrs. or Ms., then the delivery system  106  assigns “?” to the gender characteristic ( 912 ). Values other than “?” can also be used to indicate that the value is unknown. After assigning a “?” value, the delivery system  106  does not need to update the confidence score because it already had a confidence score of 0 for the gender characteristic for this user. 
     After attempting to infer the user&#39;s gender at step  806 , the delivery system  106  checks the confidence score ( 808 ). If the confidence score has exceeded a specified threshold, then the derivation process is complete. Alternatively, the delivery system  106  could also check the gender characteristic field to determine if a valid value has been entered. However, if the delivery system  106  is not yet confident that the derived value, if any, can reliably be used to select targeted content for the user, then the delivery system  106  fetches the user&#39;s first name at step  810  from the account database  804 . The delivery system  106  then compares the user&#39;s first name at step  812  with the U.S. Census database  814 . Using the Census data, the delivery system  106  again attempts to infer the user&#39;s gender ( 816 ).  FIG. 9B  illustrates a method  950  that can be used to infer the user&#39;s gender from the Census data. First, the delivery system  106  checks if the data skews male ( 952 ). That is, the delivery system  106  checks if the Census data indicates that the first name is predominately male. If so, the delivery system  106  assigns male to the gender characteristic ( 954 ) and assigns a confidence score ( 960 ). In this case, the confidence score is assigned based on the probability that the first name is male. Historically, there are certain first names that are traditionally only given to males or females, some that lean towards one sex, and others that are completely unisex. If the data does not skew male, then the delivery system  106  checks if the data skews female ( 956 ). If so, the delivery system  106  assigns female to the gender characteristic ( 958 ) and assigns a confidence score ( 960 ). If the delivery system  106  is unable to infer a gender from the Census data, then the delivery system  106  assigns “?” to the gender characteristic ( 962 ). 
     After attempting to infer the user&#39;s gender at step  816 , the delivery system  106  again checks the confidence score ( 818 ). If the confidence score has exceeded a specified threshold, then the derivation process is complete. However, if the delivery system  106  is not yet confident in the derived value, which can happen if the Census data is only slightly skewed towards one gender, then the delivery system  106  fetches the user&#39;s purchase history from the account database  821  at step  820 . The account database  821  can be the same database as account database  804 . Using the purchase history, the delivery system  106  again attempts to infer the user&#39;s gender ( 822 ). The method  950 , illustrated in  FIG. 9B , can again be used to infer the user&#39;s gender, only this time from the purchase history. First, the delivery system  106  checks if the data skews male ( 952 ). That is, the delivery system  106  checks if the categories from which the user purchased content are those predominately purchased by male users. If so, the delivery system  106  assigns male to the gender characteristic ( 954 ) and assigns a confidence score ( 960 ). If the purchase history data does not skew male, then the delivery system  106  checks if the data skews female ( 956 ). If so, the delivery system  106  assigns female to the gender characteristic ( 958 ) and assigns a confidence score ( 960 ). If the delivery system  106  still cannot infer whether the user is male or female, then the delivery system  106  assigns “?” to the user&#39;s gender characteristic ( 962 ). 
     At this point, the delivery system  106  has used all available data in an attempt to derive the unknown characteristic. If the characteristic is still unknown at the end of the method  800 , then the delivery system  106  can make another attempt to derive the data at a later time or by a different methodology, such as the population similarity method illustrated through  FIGS. 7A and 7B  discussed above. 
     In some embodiments, the delivery system  106  can receive a direct request to derive one or more unknown user characteristic values and/or a request can be included with a request for invitational content. In some embodiments, the delivery system  106  can derive the uncertain characteristic value in response to a need for the value, such as when the delivery system  106  is assigning a user to a particular targeted segment that relies on the value. In some embodiments, the delivery system  106  can derive uncertain user characteristic values at regular intervals. 
       FIG. 10  illustrates another example of deriving an uncertain user characteristic value. The method  1000  in  FIG. 10  can be used to derive a current zip code characteristic value. The derivation method  1000  begins at  1002 , where the delivery system  106  maps the user&#39;s current location to a zip code. In some embodiments, the user&#39;s location can be provided as a latitude and/or longitude value, however, other methods of expressing location are also possible. The location value can be provided as part of the request for a content package or can be obtained through other interaction with the user. To map the location to a zip code, the delivery system  106  queries the location database  1004 . The delivery system  106  then checks if the value returned from the location database  1004  is valid ( 1006 ). Checking for validity can be as simple as verifying that the zip code value is composed of valid characteristics and is an appropriate length. If the zip code value is not valid, then the delivery system  106  can assign “?” to the current zip code characteristic ( 1008 ). Values other than “?” can also be used to indicate that the value is unknown. Otherwise, the delivery system  106  assigns the returned zip code value to the current zip code characteristic ( 1010 ). In some embodiments, the delivery system  106  can also assign a confidence score to the current zip code characteristic. Once the value is derived, the delivery system  106  can update the user&#39;s profile in the user profile database  120  and/or use the data during the session to aid in selecting appropriate invitational content. 
     After completing the derivation method  1000 , there are a number of cases in which the delivery system  106  may need to repeat this action. Such scenarios include, but are not limited to, at the end of method  1000  the current zip code characteristic is still unknown, an assigned confidence score is less than a threshold value, the user&#39;s location changed, and/or a specified period of time has expired. 
       FIG. 11  illustrates another example of deriving an uncertain user characteristic value. The method  1100  in  FIG. 11  can be used to derive a home zip code characteristic value. The derivation method  1100  begins at  1102 , where the delivery system  106  fetches the user&#39;s billing information from an account database  1104 . The account database  1104  can be the user profile database  120  or it could be another database, such as the ITUNES database maintained by Apple Inc. of Cupertino, Calif., which stores user account information. The delivery system  106  then checks the billing information to see if it contains a zip code ( 1106 ). If there is a zip code, then delivery system  106  assigns it to the home zip code characteristic ( 1110 ). In some embodiments, the delivery system  106  can verify that the zip code value is valid prior to assigning it to the home zip code characteristic. Checking for validity can be as simple as verifying that the zip code value is composed of valid characteristics and is an appropriate length. However, if the billing information is lacking a zip code, the delivery system  106  checks the billing information for a street and city ( 1108 ). If the billing information also lacks this information, the delivery system  106  assigns “?” to the home zip code characteristic ( 1112 ). Values other than “?” can also be used to indicate that the value is unknown. If the delivery system  106  did find a street and city in the billing information, the delivery system  106  maps the information to a zip code ( 1114 ). To map the street and city to a zip code the delivery system  106  queries the address database  1116 . The delivery system  106  then checks if the value returned from the address database  1116  is valid ( 1118 ). If the zip code value is not valid, then the delivery system  106  can assign “?” to the home zip code characteristic ( 1120 ). Otherwise, the delivery system  106  assigns the returned zip code value to the home zip code characteristic ( 1122 ). In some embodiments, the delivery system  106  can also assign a confidence score to the home zip code characteristic. Once the value is derived, the delivery system  106  can update the user&#39;s profile in the user profile database  120  and/or use the data during the session to aid in selecting appropriate invitational content. 
     After completing the derivation method  1100 , there are a number of cases in which the delivery system  106  may need to repeat this action. Such scenarios include, but are not limited to, at the end of method  1100  the home zip code characteristic is still unknown, an assigned confidence score is less than a threshold value, the user&#39;s billing information changes, and/or a specified period of time has expired. 
       FIG. 12  illustrates another example of deriving an uncertain user characteristic. The method  1200  in  FIG. 12  can be used to derive a current city characteristic value. The derivation method  1200  begins at  1202 , where the delivery system  106  maps the user&#39;s current location to a city. In some embodiments, the user&#39;s location can be provided as a latitude and/or longitude value, however, other methods of expressing location are also possible. The location value can be provided as part of the request for a content package or can be obtained through other interactions with the user. To map the location to a city, the delivery system  106  queries the location database  1204 . The delivery system  106  then checks if the value returned from the location database  1204  is valid ( 1206 ). Checking for validity can be as simple as verifying that the value is non-null, that the value is composed of valid characters, or that the value is the name of a known city. If the city value is not valid, then the delivery system  106  can assign “?” to the current city characteristic ( 1208 ). Values other than “?” can also be used to indicate that the value is unknown. Otherwise, the delivery system  106  assigns the returned city value to the current city characteristic ( 1210 ). In some embodiments, the delivery system  106  can also assign a confidence score to the current city characteristic. Once the value is derived, the delivery system  106  can update the user&#39;s profile in the user profile database  120  and/or use the data during the session to aid in selecting appropriate invitational content. 
     After completing the derivation method  1200 , there are a number of cases in which the delivery system  106  may need to repeat this action. Such scenarios include, but are not limited to, at the end of method  1200  the current city characteristic is still unknown, an assigned confidence score is less than a threshold value, the user&#39;s location changed, and/or a specified period of time has expired. 
       FIG. 13  illustrates another example of deriving an uncertain user characteristic value. The method  1300  in  FIG. 13  can be used to derive a home city characteristic value. The derivation method  1300  begins at  1302 , where the delivery system  106  fetches the user&#39;s billing information from an account database  1304 . The account database  1304  can be the user profile database  120  or it could be another database, such as the ITUNES database maintained by Apple Inc. of Cupertino, Calif., which stores user account information. The delivery system  106  then checks the billing information to see if it contains a city ( 1306 ). If there is a city, then delivery system  106  assigns it to the home city characteristic ( 1310 ). However, if the billing information is lacking a city, the delivery system  106  checks the billing information for a zip code ( 1308 ). If the billing information also lacks this information, the delivery system  106  assigns “?” to the home city characteristic ( 1312 ). Values other than “?” can also be used to indicate that the value is unknown. If the delivery system  106  did find a zip code in the billing information, the delivery system  106  maps the information to a city ( 1314 ). To map the zip code to a city the delivery system  106  queries the address database  1316 . The delivery system  106  then checks if the value returned from the address database  1316  is valid ( 1318 ). Checking for validity can be as simple as verifying that the value is non-null, that the value is composed of valid characters, or that the value is the name of a known city. If the city value is not valid, then the delivery system  106  can assign “?” to the home city characteristic ( 1320 ). Otherwise, the delivery system  106  assigns the returned city value to the home city characteristic ( 1322 ). In some embodiments, the delivery system  106  can also assign a confidence score to the home city characteristic. Once the value is derived, the delivery system  106  can update the user&#39;s profile in the user profile database  120  and/or use the data during the session to aid in selecting appropriate invitational content. 
     After completing the derivation method  1300 , there are a number of cases in which the delivery system  106  may need to repeat this action. Such scenarios include, but are not limited to, at the end of method  1300  the home city characteristic is still unknown, an assigned confidence score is less than a threshold value, the user&#39;s billing information changes, and/or a specified period of time has expired. 
       FIG. 14  illustrates another example of deriving an uncertain user characteristic value. The method  1400  in  FIG. 14  can be used to derive a current designated market area (DMA) characteristic value. The derivation method  1400  begins at  1402 , where the delivery system  106  maps the user&#39;s current location to a DMA. In some embodiments, the user&#39;s location can be provided as a latitude and/or longitude value, however, other methods of expressing location are also possible. The location value can be provided as part of the request for a content package or can be obtained through other interaction with the user. To map the location to a DMA, the delivery system  106  queries the location database  1404 . The delivery system  106  then checks if the value returned from the location database  1404  is valid ( 1406 ). Checking for validity can be as simple as verifying that the value is non-null, that the value is composed of valid characters, or that the value is the name of a known DMA. If the DMA value is not valid, then the delivery system  106  can assign “?” to the current DMA characteristic ( 1408 ). Values other than “?” can also be used to indicate that the value is unknown. Otherwise, the delivery system  106  assigns the returned DMA value to the current DMA characteristic ( 1410 ). In some embodiments, the delivery system  106  can also assign a confidence score to the current DMA characteristic. Once the value is derived, the delivery system  106  can update the user&#39;s profile in the user profile database  120  and/or use the data during the session to aid in selecting appropriate invitational content. 
     After completing the derivation method  1400 , there are a number of cases in which the delivery system  106  may need to repeat this action. Such scenarios include, but are not limited to, at the end of method  1400  the current DMA characteristic is still unknown, an assigned confidence score is less than a threshold value, the user&#39;s location changed, and/or a specified period of time has expired. 
       FIG. 15  illustrates another example of deriving an uncertain user characteristic value. The method  1500  in  FIG. 15  can be used to derive a home designated market area (DMA) characteristic value. The derivation method  1500  begins at  1502 , where the delivery system  106  fetches the user&#39;s billing information from an account database  1504 . The account database  1504  can be the user profile database  120  or it could be another database, such as the ITUNES database maintained by Apple Inc. of Cupertino, Calif., which stores user account information. The delivery system  106  then checks the billing information to see if it contains a zip code ( 1506 ). If the billing information lacks a zip code, the delivery system  106  assigns “?” to the home DMA characteristic ( 1508 ). However, if the delivery system  106  did find a zip code in the billing information, the delivery system  106  maps the information to a DMA ( 1510 ). To map the zip code to a DMA, the delivery system  106  queries the DMA database  1512 . The delivery system  106  then checks if the value returned from the DMA database  1512  is valid ( 1514 ). Checking for validity can be as simple as verifying that the value is non-null, that the value is composed of valid characters, or that the value is the name of a known DMA. If the DMA value is not valid, then the delivery system  106  can assign “?” to the home DMA characteristic ( 1516 ). Otherwise, the delivery system  106  assigns the returned DMA value to the home DMA characteristic ( 1518 ). In some embodiments, the delivery system  106  can also assign a confidence score to the home DMA characteristic. Once the value is derived, the delivery system  106  can update the user&#39;s profile in the user profile database  120  and/or use the data during the session to aid in selecting appropriate invitational content. 
     After completing the derivation method  1500 , there are a number of cases in which the delivery system  106  may need to repeat this action. Such scenarios include, but are not limited to, at the end of method  1500  the home DMA characteristic is still unknown, an assigned confidence score is less than a threshold value, the user&#39;s billing information changes, and/or a specified period of time has expired. 
       FIG. 16  illustrates another example of deriving an uncertain user characteristic value. The method  1600  in  FIG. 16  can be used to derive a country characteristic value. The derivation method  1600  begins at  1602 , where the delivery system  106  maps the user&#39;s mobile country code (MCC) to a country. In some embodiments, the user&#39;s MCC value can be provided as part of the request for a content package or can be obtained through other interaction with the user. To map the MCC to a country, the delivery system  106  queries the country database  1604 . The delivery system  106  then checks if the value returned from the country database  1604  is valid ( 1606 ). Checking for validity can be as simple as verifying that the value is non-null, that the value is composed of valid characters, or that the value is the name of a known country. If the country value is not valid, then the delivery system  106  can assign “?” to the current country characteristic ( 1608 ). Values other than “?” can also be used to indicate that the value is unknown. Otherwise, the delivery system  106  assigns the returned country value to the country characteristic ( 1610 ). In some embodiments, the delivery system  106  can also assign a confidence score to the country characteristic. Once the value is derived, the delivery system  106  can update the user&#39;s profile in the user profile database  120  and/or use the data during the session to aid in selecting appropriate invitational content. 
     After completing the derivation method  1600 , there are a number of cases in which the delivery system  106  may need to repeat this action. Such scenarios include, but are not limited to, at the end of method  1600  the country characteristic is still unknown, an assigned confidence score is less than a threshold value, the user&#39;s MCC changed, and/or a specified period of time has expired. 
       FIG. 17  illustrates another example of deriving an uncertain user characteristic value. The method  1700  in  FIG. 17  can be used to derive a current time zone characteristic value. The derivation method  1700  begins at  1702 , where the delivery system  106  maps the user&#39;s current location to a time zone. In some embodiments, the user&#39;s location can be provided as a latitude and/or longitude value, however, other methods of expressing location are also possible. The location value can be provided as part of the request for a content package or can be obtained through other interaction with the user. To map the location to a time zone, the delivery system  106  queries the location database  1704 . The delivery system  106  then checks if the value returned from the location database  1704  is valid ( 1706 ). Checking for validity can be as simple as verifying that the value is non-null, that the value is composed of valid characters, or that the value is the name of a known time zone. If the time zone value is not valid, then the delivery system  106  can assign “?” to the current time zone characteristic ( 1708 ). Values other than “?” can also be used to indicate that the value is unknown. Otherwise, the delivery system  106  assigns the returned time zone value to the current time zone characteristic ( 1710 ). In some embodiments, the delivery system  106  can also assign a confidence score to the current time zone characteristic. Once the value is derived, the delivery system  106  can update the user&#39;s profile in the user profile database  120  and/or use the data during the session to aid in selecting appropriate invitational content. 
     After completing the derivation method  1700 , there are a number of cases in which the delivery system  106  may need to repeat this action. Such scenarios include, but are not limited to, at the end of method  1700  the current time zone characteristic is still unknown, an assigned confidence score is less than a threshold value, the user&#39;s location changed, and/or a specified period of time has expired. 
       FIG. 18  illustrates another example of deriving an uncertain user characteristic value. The method  1800  in  FIG. 18  can be used to derive a home time zone characteristic value. The derivation method  1800  begins at  1802 , where the delivery system  106  fetches the user&#39;s billing information from an account database  1804 . The account database  1804  can be the user profile database  120  or it could be another database, such as the ITUNES database maintained by Apple Inc. of Cupertino, Calif., which stores user account information. The delivery system  106  then maps the billing information to a time zone ( 1806 ). To map the billing information to a time zone, the delivery system  106  queries the time zone database  1808 . The query could be based on the entire billing address, the zip code, the city and state, or any combination of values found in the billing address. The delivery system  106  then checks if the value returned from the location database  1808  is valid ( 1810 ). Checking for validity can be as simple as verifying that the value is non-null, the value is a single value, that the value is composed of valid characters, or that the value is the name of a known time zone. If the time zone value is not valid, then the delivery system  106  can assign “?” to the current time zone characteristic ( 1812 ). Values other than “?” can also be used to indicate that the value is unknown. Otherwise, the delivery system  106  assigns the returned time zone value to the home time zone characteristic ( 1814 ). In some embodiments, the delivery system  106  can also assign a confidence score to the home time zone characteristic. Once the value is derived, the delivery system  106  can update the user&#39;s profile in the user profile database  120  and/or use the data during the session to aid in selecting appropriate invitational content. 
     After completing the derivation method  1800 , there are a number of cases in which the delivery system  106  may need to repeat this action. Such scenarios include, but are not limited to, at the end of method  1800  the home time zone characteristic is still unknown, an assigned confidence score is less than a threshold value, the user&#39;s billing information changed, and/or a specified period of time has expired. 
       FIG. 19  illustrates another example of deriving an uncertain user characteristic value. The method  1900  in  FIG. 19  can be used to derive a date and day part characteristic value. The date and day part user characteristic is associated with a day and time of day value. The time of day can be values descriptive of a time of day such as dawn, dusk, morning, noon, lunch time, afternoon, commuting hours, etc. or a particular time during the day, e.g. 7 am. The date can be a particular day of the week, e.g. Monday; a value descriptive of a part of the week, e.g. workday, weekend; a day of the month, e.g. January 1; or any other value that describes a date. 
     The derivation method  1900  begins at  1902 , where the delivery system  106  maps the user&#39;s current location to a time zone. In some embodiments, the user&#39;s location can be provided as a latitude and/or longitude value, however, other methods of expressing location are also possible. The location value can be provided as part of the request for a content package or can be obtained through other interactions with the user. To map the location to a time zone, the delivery system  106  queries the location database  1904 . The delivery system  106  then checks if the value returned from the location database  1904  is valid ( 1906 ). Checking for validity can be as simple as verifying that the value is non-null, that the value is composed of valid characters, or that the value is the name of a known time zone. If the time zone value is not valid, then the delivery system  106  can assign “?” to the date and day part characteristic ( 1908 ). Values other than “?” can also be used to indicate that the value is unknown. Otherwise, the delivery system  106  uses the time zone value to map the server time to local device time ( 1910 ). Based on the local device time, the delivery system  106  assigns the date and day part value to the date and day part characteristic ( 1912 ). In some embodiments, the delivery system  106  can also assign a confidence score to the date and day part characteristic. Once the value is derived, the delivery system  106  can update the user&#39;s profile in the user profile database  120  and/or use the data during the session to aid in selecting appropriate invitational content. 
     After completing the derivation method  1900 , there are a number of cases in which the delivery system  106  may need to repeat this action. Such scenarios include, but are not limited to, at the end of method  1900  the date and day part characteristic is still unknown, an assigned confidence score is less than a threshold value, the user&#39;s location changed, and/or a specified period of time has expired. 
       FIG. 20  illustrates another example of deriving an uncertain user characteristic value. The method  2000  in  FIG. 20  can be used to derive an age range characteristic value. The derivation method  2000  begins at  2002  where the delivery system  106  fetches the purchase history from an account database  2004 . The account database  2004  could be the user profile database  120  or it could be another database, such as the ITUNES database maintained by Apple Inc. of Cupertino, Calif., which stores account information. After fetching the purchase history, the delivery system  106  maps the user&#39;s purchases to age ranges ( 2006 ). To map the purchased content to age ranges, the delivery system  106  queries the content age range database  2008 . The content age range database  2008  contains associated age ranges for a variety of content. This database can be populated by first manually constructing sets of representative content for each age range by genre, category, item, etc. ( 2014 ). For example, educational apps could be assigned an age range of 5-13. This type of age range classification can be performed for all types of content available for purchase, e.g. apps, music, movies, television shows, books, etc. The representative sets can then be fed to a recommendation system or similarity engine, to expand the set(s) of items ( 2012 ). 
     Using the obtained age ranges for the purchased content, the delivery system  106  picks the age range with maximum pieces of content ( 2010 ). For example, if eighty percent of the content purchased is associated with the age range 5-13, then the delivery system  106  picks the 5-13 age range. In some embodiments, the delivery system  106  can be configured to pick an age range based on the age ranges associated with a single type of content. Alternatively, the delivery system  106  can be configured to pick from the age ranges associated with multiple types of content. Finally, the delivery system  106  assigns the selected age range to the age range characteristic ( 2016 ). 
     In some cases, the delivery system may not be able to select a single age range because the user has not purchased any content, the content is evenly distributed across multiple age ranges, or the content distribution does not weigh heavily enough towards one age range. In this case, the delivery system  106  can assign “?” to the age range characteristic. Values other than “?” can also be used to indicate that the value is unknown. In some embodiments, the delivery system  106  can also assign a confidence score to the age range characteristic. Once the value is derived, the delivery system  106  can update the user&#39;s profile in the user profile database  120  and/or use the data during the session to aid in selecting appropriate invitational content. 
     After completing the derivation method  2000 , there are a number of cases in which the delivery system  106  may need to repeat this action. Such scenarios include, but are not limited to, at the end of method  2000  the age range characteristic is still unknown, an assigned confidence score is less than a threshold value, the user&#39;s purchase history has changed, and/or a specified period of time has expired. 
       FIG. 21  illustrates another example of deriving an uncertain user characteristic value. The method  2100  in  FIG. 21  can be used to derive life stage and marital status characteristic values. The derivation method  2100  begins at  2102 , where the delivery system  106  fetches the user&#39;s address from an account database  2104 . The account database  2104  can be the user profile database  120  or it could be another database, such as the ITUNES database maintained by Apple Inc. of Cupertino, Calif., which stores user account information. The delivery system  106  then fetches all users with the same address from the account database  2108  ( 2106 ). The account database  2108  can be the same database as the account database  2104  or it can be another database. After collecting all users with the same address, the delivery system  106  forms a “family” unit from the users ( 2110 ). Before the delivery system  106  can characterize the users in the “family” unit, the delivery system  106  has to obtain the user characteristics for each user in the “family” unit ( 2111 ). In some embodiments, the delivery system can obtain the user characteristics from the user profile database  120 . In some cases, the gender and/or age characteristics may be missing from the user profile. In this case, the delivery system can derive the missing characteristic(s) using the methods  800  or  2000  described above or some other derivation method. 
     To derive the life stage and marital status characteristic values, the delivery system  106  examines the gender and age characteristics of each of the users in the “family” unit. First, the delivery system  106  checks if the “family” unit contains both a male and female user with age greater than the marital status age threshold, 25 in this example ( 2114 ). If the delivery system  106  identifies such users, then they are each assigned a marital status characteristic of married ( 2116 ). Any additional, users in the “family” unit can be assigned the marital status characteristic of single. If the check for a male and female user with age greater than the marital status age threshold fails, the delivery system  106  assigns a marital status characteristic value of single to each user in the “family” unit ( 2112 ). In this example the marital status age threshold is 25, however, other values can also be used for the threshold value. In some embodiments, the marital status age threshold can vary by geographic region. 
     After assigning married or single to each user in the “family” unit at step  2116 , the delivery system  106  checks for users under the child-age threshold in the “family” unit ( 2120 ). If users under the child-age threshold are identified, the delivery system  106  assigns a life stage value of child to these users and a life stage value of parent to the users identified in step  2114  ( 2126 ). If no users under the child-age threshold are identified, then husband and wife values are assigned to the life stage characteristics of the users identified in step  2114  ( 2128 ). In this example the child-age threshold is 18, however, other values can also be used for the threshold value. The child-age threshold can vary by geographic region. 
     After assigning single to each user in the “family” unit at step  2112 , the delivery system  106  checks for users under the child-age threshold in the “family” unit ( 2118 ). If users under the child-age threshold are identified, the delivery system  106  assigns a life stage value of child to these users ( 2122 ) and a life stage value of adult to any other users ( 2124 ). 
     In some embodiments, the delivery system  106  can also assign a confidence score to the life stage and marital status characteristic values. Once the value is derived, the delivery system  106  can update the user&#39;s profile in the user profile database  120  and/or use the data during the session to aid in selecting appropriate invitational content. 
     After completing the derivation method  2100 , there are a number of cases in which the delivery system  106  may need to repeat this action. Such scenarios include, but are not limited to, at the end of method  2100  the life stage and/or marital status characteristics are still unknown, an assigned confidence score is less than a threshold value, the user characteristics of one or more users in the “family” unit have changed, and/or a specified period of time has expired. 
       FIG. 22  illustrates another example of deriving an uncertain user characteristic value. The method  2200  in  FIG. 22  can be used to derive a life stage user characteristic value. The derivation method  2200  begins at  2202  where the delivery system  106  fetches the purchase history from an account database  2204 . The account database  2204  could be the user profile database  120  or it could be another database, such as the ITUNES database maintained by Apple Inc. of Cupertino, Calif., which stores account information. After fetching the purchase history, the delivery system  106  maps the user&#39;s purchases to age ranges ( 2206 ). To map the purchased content to age ranges, the delivery system  106  queries the content age range database  2208 . The content age range database  2208  contains associated age ranges for a variety of content. This database can be populated by first manually constructing sets of representative content for each age range by genre, category, item, etc. ( 2214 ). For example, educational apps could be assigned an age range of 5-13. This type of age range classification can be performed for all types of content available for purchase, e.g. apps, music, movies, television shows, books, etc. The representative sets can then be fed to a recommendation system or similarity engine, to expand the set(s) of items ( 2212 ). 
     The delivery system  106  also obtains the user&#39;s age ( 2210 ). In some cases, the delivery system  106  can obtain this information from the user profile database, from an account database, or by deriving the value from other user characteristic values known about the user. To derive the user&#39;s age, the delivery system can use method  2000  in  FIG. 20  above or any other method for deriving a user&#39;s age. Once the delivery system has the user&#39;s age, the delivery system  106  checks if the user&#39;s age is greater than the child-age threshold ( 2216 ). If the user is under the child-age threshold, the delivery system  106  assigns child to the life stage user characteristic for the user ( 2220 ). In this example the child-age threshold is 18, however, other values can also be used for the threshold value. The child-age threshold can vary by geographic region. 
     If the user is over the child-age threshold value, the delivery system  106  checks if the user is over the parent-age threshold ( 2222 ). If the user is over the child-age threshold, but under the parent-age threshold, the delivery system  106  assigns adult to the life stage user characteristic for the user ( 2224 ). If the user is over the parent-age threshold, the delivery system  106  examines the user&#39;s purchase history, which has associated age classifications, to determine if the purchase history includes content traditionally used by user&#39;s under 18 ( 2226 ). If so the, the delivery system  106  assigns a life stage value of parent to the user ( 2230 ). If not, the delivery system  106  assigns a life stage value of adult to the user ( 2228 ). In this example the parent-age threshold is 25, however, other ages can be used to demarcate the adult and parent boundaries. Additionally, the parent-age threshold can vary by geographic region. 
     In some embodiments, the delivery system  106  can also assign a confidence score to the life stage characteristic. Once the value is derived, the delivery system  106  can update the user&#39;s profile in the user profile database  120  and/or use the data during the session to aid in selecting appropriate invitational content. 
     After completing the derivation method  2200 , there are a number of cases in which the delivery system  106  may need to repeat this action. Such scenarios include, but are not limited to, at the end of method  2200  the life stage characteristic is still unknown, an assigned confidence score is less than a threshold value, the age and/or purchase history of the user have changed, and/or a specified period of time has expired. 
       FIG. 23  illustrates another example of deriving an uncertain user characteristic value. The method  2300  in  FIG. 20  can be used to derive an ethnicity characteristic value. The derivation method  2300  begins at  2302  where the delivery system  106  fetches the purchase history from an account database  2304 . The account database  2304  could be the user profile database  120  or it could be another database, such as the ITUNES database maintained by Apple Inc. of Cupertino, Calif., which stores account information. After fetching the purchase history, the delivery system  106  maps the user&#39;s purchases to language codes ( 2306 ). To map the purchased content to language codes, the delivery system  106  queries the language code database  2307 . The language code database  2307  can again be another database, such as the ITUNES database maintained by Apple Inc. of Cupertino, Calif., or any other database or multiple databases with such information. In some embodiments, the delivery system  106  may not need to perform step  2307  because the purchase history will already contain the associated language codes. 
     After obtaining the language codes, the delivery system  106  checks if the language codes are Japanese, Chinese, or Korean ( 2308 ). If the check at step  2308  is true, the delivery system  106  assigns Asian to the ethnicity characteristic ( 2310 ) and the derivation method is complete. However, if the check at step  2308  fails, the delivery system  106  checks if the language codes are Spanish ( 2312 ). If the check at step  2312  is true, the delivery system  106  assigns Latino to the ethnicity characteristic ( 2314 ) and the derivation method is complete. 
     If the check at step  2312  fails, the delivery system  106  can draw on other user characteristics to derive the ethnicity characteristic. First, the delivery system  106  fetches the user&#39;s first and last name from the account database  2317  ( 2316 ). In some embodiments, the account database  2317  can be the same database as account database  2304 . Alternatively, the account database  2317  can be a separate database that stores user account information. The delivery system  106  then compares the user&#39;s first and last name at step  2318  with the U.S. Census database  2320 , or any other census database. Using the Census data, the delivery system  106  checks if the data skews towards one single ethnic background ( 2322 ). If the data does lean towards a single ethnic background, the delivery system  106  assigns the ethnicity value to the ethnicity characteristic ( 2324 ). In some embodiments, the delivery system  106  can assign a confidence score to the ethnicity value at this point based on how heavily the data is skewed towards a single ethnic background. 
     If the census data does not skew towards a single ethnic background, the delivery system  106  can then examine the user&#39;s music purchase history to attempt to derive the user&#39;s ethnicity. First, the delivery system  106  fetches the user&#39;s music purchase history from the account database  2327  ( 2326 ). In some embodiments, the account database  2327  can be the same database as account database  2304  and/or account database  2317 . In some embodiments, the delivery system  106  can skip step  2326  and instead extract the music purchase history from the purchase history information obtained in step  2302 . Once the delivery system  106  obtains the music purchase history, the delivery system  106  maps it to content categories ( 2328 ), such as Country, Hip-Hop, Latino, World, etc. The mapping is accomplished by querying a content category database  2030 . If the music purchase history indicates that 80% of purchases are in the Country music category or the music purchase history does not include any music from the World music category, then the delivery system  106  assigns Caucasian to the ethnicity characteristic ( 2332 ). If the purchase history indicates that 80% of purchases are in the Latino music category then the delivery system  106  assigns Latino to the ethnicity characteristic ( 2334 ). Otherwise, the delivery system  106  assigns “?” to the ethnicity characteristic ( 2338 ). Values other than “?” can also be used to indicate that the value is unknown. In some embodiments, other rules for analyzing the music categories to infer ethnicity can also be used. 
     In some embodiments, the delivery system  106  can also assign a confidence score to the ethnicity characteristic. Once the value is derived, the delivery system  106  can update the user&#39;s profile in the user profile database  120  and/or use the data during the session to aid in selecting appropriate invitational content. 
     After completing the derivation method  2300 , there are a number of cases in which the delivery system  106  may need to repeat this action. Such scenarios include, but are not limited to, at the end of method  2300  the ethnicity characteristic is still unknown, an assigned confidence score is less than a threshold value, the user&#39;s purchase history has changed, and/or a specified period of time has expired. 
       FIG. 24  illustrates another example of deriving an uncertain user characteristic value. The method  2400  in  FIG. 24  can be used to derive an income characteristic value. The derivation method  2400  begins at  2402 , where the delivery system  106  fetches the user&#39;s billing information from an account database  2404 . The account database  2404  can be the user profile database  120  or it could be another database, such as the ITUNES database maintained by Apple Inc. of Cupertino, Calif., which stores user account information. The delivery system  106  then compares the user&#39;s billing information at step  2406  with the U.S. Census database  2408 , or any other census database, to obtain data on average income levels where the user lives. The delivery system  106  can also compare the user&#39;s billing information with one or more other third party databases  2412  ( 2410 ) to gather more data on income levels where the user lives. After obtaining data from a variety of sources, the delivery system  106  analyzes the data at step  2414 . Based on the analysis, the delivery system generates an income estimate for the user and assigns it to the income characteristic ( 2416 ). 
     In some embodiments, the delivery system can use other information to infer the user&#39;s income. For example, if the delivery system  106  has access to the user&#39;s occupation this information could aid in refining an estimate of the user&#39;s income. Purchase history could also possibly aid in deriving the user&#39;s income. 
     In some embodiments, the delivery system  106  can also assign a confidence score to the income characteristic. Once the value is derived, the delivery system  106  can update the user&#39;s profile in the user profile database  120  and/or use the data during the session to aid in selecting appropriate invitational content. 
     After completing the derivation method  2400 , there are a number of cases in which the delivery system  106  may need to repeat this action. Such scenarios include, but are not limited to, at the end of method  2400  the income characteristic is still unknown, an assigned confidence score is less than a threshold value, the user&#39;s account information has changed, and/or a specified period of time has expired. 
       FIG. 25  illustrates another example of deriving an uncertain user characteristic value. The method  2500  in  FIG. 25  can be used to derive a preferred purchase categories characteristic value. The derivation method  2500  begins at  2502  where the delivery system  106  fetches the purchase history from an account database  2504 . The account database  2504  could be the user profile database  120  or it could be another database, such as the ITUNES database maintained by Apple Inc. of Cupertino, Calif., which stores account information. After fetching the purchase history, the delivery system  106  maps the purchased content to categories/genres ( 2506 ). To map the purchased content to categories/genres, the delivery system  106  queries the content category database  2508 . The content category database  2508  can be another database, such as the ITUNES database maintained by Apple Inc. of Cupertino, Calif., or any other database or multiple databases with such information. Using the category mapping, the delivery system  106  examines the user&#39;s preferred purchase categories for each content type independently, e.g. apps, music, movies, television shows, etc. At step  2510 , the delivery system checks if there are content types for which the system still needs to create a preference list. If there are, the delivery system  106  generates a frequency distribution for the purchases for the content type, e.g. app, by category at step  2512 . Then the delivery system  106  computes the percentages each category represents out of the total purchases for the content type ( 2514 ). For example, if the app categories were social networking and sports, the delivery system would determine what percentage of app purchase were social networking apps and what percentage where sports apps. Then for each of the categories the delivery system adds the category to the preferred categories list if the percentage computed at step  2514  is greater than 20% ( 2516 ). In some embodiments, a higher or lower percentage can be used when determining whether a particular category should be considered preferred. Finally, the system assigns the list of preferred categories to the preferred categories characteristic for that content type ( 2518 ). After assigning the values to the characteristic, the delivery system loops back to step  2510  to check if there are other content types to process. 
     In some embodiments, the delivery system  106  can also assign a confidence score to the one or more preferred purchase categories characteristics. Once the value is derived, the delivery system  106  can update the user&#39;s profile in the user profile database  120  and/or use the data during the session to aid in selecting appropriate invitational content. 
     After completing the derivation method  2500 , there are a number of cases in which the delivery system  106  may need to repeat this action. Such scenarios include, but are not limited to, at the end of method  2500  one or more preferred purchase category characteristics is still unknown, an assigned confidence score is less than a threshold value, the user&#39;s purchase history has changed, and/or a specified period of time has expired. 
       FIG. 26  illustrates another example of deriving an uncertain user characteristic value. The method  2600  in  FIG. 26  can be used to derive a spend level characteristic value. The derivation method  2600  begins at  2602  where the delivery system  106  fetches the purchase history from an account database  2604 . The account database  2604  could be the user profile database  120  or it could be another database, such as the ITUNES database maintained by Apple Inc. of Cupertino, Calif., which stores account information. At step  2606 , the delivery system checks if there are content types for which the spend level characteristic still needs to be derived. If there are, the delivery system  106  calculates the total amount spent over the last 30 days for that content type, e.g. music ( 2608 ). In some embodiments, other time periods can also be used. For example the spend level can be based on a 1 year time period, 6 months, 1 week, etc. 
     In some embodiments, the spend level characteristic can be a relative characteristic where deciles are generated based on the spending habits of other users or deciles are generated based on a predefined scale. In either case, the delivery system  106  fetches the spend level deciles for the content type from the deciles database  2612  ( 2610 ). The deciles database  2612  can be the same database as the account database  2604  or any other database or even multiple databases. In some embodiments, the deciles database  2612  can be different databases for the different content types. After the delivery system  106  has calculated the amount spent by the user and obtained the spend level deciles, the delivery system  106  identifies the decile to which the user belongs ( 2614 ). In some embodiments, the deciles can be ranked and assigned numbers such as decile 1, decile 2, etc. In some embodiments, the deciles are simply ranges. 
     Once the delivery system  106  has identified the user&#39;s decile, the delivery system  106  checks if the user&#39;s decile is in the top 1-3 deciles ( 2616 ). If so, the delivery system  106  assigns “high” to the spend level characteristic for the content type, e.g. music spend level characteristic ( 2620 ). If the user is not in deciles 1-3, then the delivery system  106  checks if the user&#39;s decile is 4-7 ( 2618 ). If so, the delivery system  106  assigns “medium” to the user&#39;s spend level for the content type ( 2622 ). If the user is not in deciles 1-3 or 4-7 then the delivery system assigns “low” to the spend level characteristic for the content type ( 2624 ). 
     In some embodiments, the spend level characteristic can be derived for each category/genre of the content type. For example, the user&#39;s spend level can be calculated for each music genre, e.g. country music category spend level, reggae music category spend level, etc. In some embodiments, the spend level characteristic can be derived for all content types together. 
     In some embodiments, the delivery system  106  can also assign a confidence score to the one or more spend level characteristics. Once the value is derived, the delivery system  106  can update the user&#39;s profile in the user profile database  120  and/or use the data during the session to aid in selecting appropriate invitational content. 
     After completing the derivation method  2600 , there are a number of cases in which the delivery system  106  may need to repeat this action. Such scenarios include, but are not limited to, at the end of method  2600  one or more spend level characteristics is still unknown, an assigned confidence score is less than a threshold value, the user&#39;s purchase history has changed, and/or a specified period of time has expired. 
       FIG. 27  illustrates another example of deriving an uncertain user characteristic value. The method  2700  in  FIG. 27  can be used to derive a purchase frequency characteristic value. The derivation method  2700  begins at  2702  where the delivery system  106  fetches the purchase history from an account database  2704 . The account database  2704  could be the user profile database  120  or it could be another database, such as the ITUNES database maintained by Apple Inc. of Cupertino, Calif., which stores account information. At step  2706 , the delivery system checks if there are content types for which the purchase frequency characteristic still needs to be derived. If there are, the delivery system  106  calculates the purchase frequency based on the purchase&#39;s timestamps over the last month for that content type ( 2708 ). In some embodiments, other time periods can also be used. For example the purchase frequency can be based on a 1 year time period, 6 months, 1 week, etc. 
     In some embodiments, the purchase frequency characteristic can be a relative characteristic where deciles are generated based on the purchasing habits of other users or deciles can be generated based on a predefined scale. In either case, the delivery system  106  fetches the purchase frequency deciles for the content type from the deciles database  2712  ( 2710 ). The deciles database  2712  can be the same database as the account database  2704  or any other database or even multiple databases. In some embodiments, the deciles database  2712  can be different databases for the different content types. 
     After the delivery system  106  has calculated the purchase frequency by the user and obtained the purchase frequency deciles, the delivery system  106  identifies the decile to which the user belongs ( 2714 ). In some embodiments, the deciles can be ranked and assigned numbers such as decile 1, decile 2, etc. In some embodiments, the deciles are simply ranges. 
     Once the delivery system  106  has identified the user&#39;s decile, the delivery system  106  checks if the user&#39;s decile is in the top 1-3 deciles ( 2716 ). If so, the delivery system  106  assigns “high” to the purchase frequency characteristic for the content type, e.g. music purchase frequency characteristic ( 2720 ). If the user is not in deciles 1-3, then the delivery system  106  checks if the user&#39;s decile is 4-7 ( 2718 ). If so, the delivery system  106  assigns “medium” to the user&#39;s purchase frequency for the content type ( 2722 ). If the user is not in deciles 1-3 or 4-7 then the delivery system assigns “low” to the purchase frequency characteristic for the content type ( 2724 ). 
     In some embodiments, the purchase frequency characteristic can be derived for each category/genre of the content type. For example, the user&#39;s purchase frequency can be calculated for each music genre, e.g. country music category purchase frequency, reggae music category purchase frequency, etc. In some embodiments, the purchase frequency characteristic can be derived for all content types together. 
     In some embodiments, the delivery system  106  can also assign a confidence score to the one or more purchase frequency characteristics. Once the value is derived, the delivery system  106  can update the user&#39;s profile in the user profile database  120  and/or use the data during the session to aid in selecting appropriate invitational content. 
     After completing the derivation method  2700 , there are a number of cases in which the delivery system  106  may need to repeat this action. Such scenarios include, but are not limited to, at the end of method  2700  one or more purchase frequency characteristics is still unknown, an assigned confidence score is less than a threshold value, the user&#39;s purchase history has changed, and/or a specified period of time has expired. 
       FIG. 28  illustrates another example of deriving an uncertain user characteristic value. The method  2800  in  FIG. 28  can be used to derive a work-home-commute characteristic value. The derivation method  2800  begins at  2802 , where the delivery system  106  maps the user&#39;s current location to a zone within a map of residentially-zoned areas, commuting corridors, and commercially-zoned areas. In some embodiments, the user&#39;s location can be provided as a latitude and/or longitude value, however, other methods of expressing location are also possible. The location value can be provided as part of the request for a content package or can be obtained through other interaction with the user. To map the location to a zone, the delivery system  106  queries the location database  2804 . The delivery system  106  then checks if the value returned from the location database  2804  is a residentially-zoned area ( 2806 ). If so, the delivery system  106  assigns the value “home” to the work-home-commute characteristic ( 2808 ). If the user&#39;s zone is not in a residentially-zoned area, the delivery system  106  checks if the user&#39;s zone is in a commuting corridor ( 2810 ). If so, the delivery system  106  assigns the value “commuting” to the work-home-commute characteristic ( 2812 ). If not, the delivery system  106  checks if the user&#39;s zone is in a commercially-zoned area ( 2814 ). If so, the delivery system  106  assigns the value work to the work-home-commute characteristic ( 2816 ). If not, the delivery system  106  assigns the value “?” to the work-home-commute characteristic ( 2818 ). Values other than “?” can also be used to indicate that the value is unknown. 
     In some embodiments, the delivery system  106  can also assign a confidence score to the work-home-commute characteristic. Once the value is derived, the delivery system  106  can update the user&#39;s profile in the user profile database  120  and/or use the data during the session to aid in selecting appropriate invitational content. 
     After completing the derivation method  2800 , there are a number of cases in which the delivery system  106  may need to repeat this action. Such scenarios include, but are not limited to, at the end of method  2800  the work-home-commute characteristic is still unknown, an assigned confidence score is less than a threshold value, the user&#39;s location changed, and/or a specified period of time has expired. 
     In some embodiments, the delivery system  106  is configured to permit content providers  109  and  110  to create custom targeted segments. Accordingly, a user interface (UI) can be provided for communicating with a user interface module  111  for performing such tasks. The UI for UI module  111  can be accessed via an end user terminal in communication with the delivery system  106 . For example, the end user terminal can be a user interface device associated with any of content providers  109  and  110 . The UI and UI module  111  can be configured to operate in a variety of client modes, including a fat client mode, a thin client mode, or a hybrid client mode, depending on the storage and processing capabilities of the delivery system  106  and/or the end user terminal. Therefore, a UI for UI module  111  can be implemented as a standalone application operating at the end user terminal in some embodiments. In other embodiments, a web browser-based portal can also be used to provide the UI for the UI module  111 . Any other configuration to remotely or locally access the delivery system  111  can also be used in the various embodiments. The UI and UI module  111  can be configured to provide content providers the ability to manipulate, select, and customize targeted segments. 
       FIG. 29  is a flowchart illustrating steps in an exemplary method  2900  for generating custom targeted segments. For the sake of clarity, this method is discussed in terms of an exemplary system such as is shown in  FIG. 1 . Although specific steps are shown in  FIG. 29 , in other embodiments a method can have more or less steps than shown. 
     To generate a custom segment the delivery system  106  identifies a collection of characteristic values from a plurality of characteristics managed by the delivery system  106  ( 2902 ). The delivery system  106  can contain a set of predefined user characteristics such as any of the channel, demographic, behavioral, and/or spatial-temporal characteristics described above, including derived characteristics, and/or any other characteristics descriptive of a user or a user&#39;s interaction with one or more items of targeted content. For example, gender, age, and occupation are all demographic characteristics that can be predefined in the delivery system  106 . 
     In some embodiments, the delivery system  106  analyzes a group of users to identify a collection of characteristics common to a specified percentage of the users. The group of users can be selected in any way, e.g. all users with a common characteristic value; users associated with a past electronic campaign that meet a specified performance criteria, e.g. all users that completed the associated conversion action, etc. 
     In some embodiments, the delivery system  106  identifies the collection of characteristic values based on input received from a content provider. In this case, the UI and UI module  111  can present the set of characteristics managed by the delivery system  106  to a content provider that is interested in using a custom targeted segment for content delivery. The content provider can then identify a collection of characteristics from that set. The collection of characteristics can be presented in a number of different ways such as through a graphical user interface (GUI) or a command-line interface. 
     In some embodiments, the UI can provide one or more selection objects (e.g. drop down boxes, check boxes, etc.) so as to enable selection of a user characteristic. In some cases, these selection objects can be linked. For example, if a country is selected in one drop down box, a state drop down box automatically filters the drop down values to only country-specific states, and so forth. In some configurations, once a user characteristic is selected, a user characteristic value selection object and/or input box appears. For example, an expandable check box can be used such that when the box is selected, the available associated values appear along with check boxes. The user characteristic value selection object can contain values specific to the associated user characteristic identifier. For example, for the gender characteristic, male and female check boxes can appear. The UI can also include a portion for content providers to input their own parameters (e.g. weights, Boolean operators, etc.). 
     The collection of characteristics can also be based upon the characteristics found in a pre-defined targeted segment. In this case, the UI can provide a selection object so as to enable selection of an existing targeted segment. Once selected, the UI can display the characteristics and any characteristic values used to define the existing targeted segment. Then the ability to add and/or remove characteristics and/or characteristic values can be provided. 
     The manner in which a content provider indicates a selection can vary with the configuration of the system. In a system configured where the collection of user characteristics is presented in a drop down box, the content provider can simply highlight a characteristic to select it. In a system configured where the collection of user characteristics is presented with an associated check box, selecting the associated check box can indicate a selection. Alternatively, entering a user characteristic in an input box can indicate a selection. 
     In some embodiments, one or more user characteristic values can be associated with a user characteristic. The delivery system  106  can contain a set of predefined values for each contextual characteristic identifier. The UI and UI module  111  can present the set of values in a number of different ways such as through a drop down box in a graphical user interface. In this case, the content provider could simply select the one or more user characteristic values desired. Alternatively, a text box can be presented and the content provider can enter a desired value. The user characteristic value can take a variety of different forms. For example, it can be a single value, e.g. female; multiple values, e.g. Jazz, Blues, Pop; or a range of values, e.g. 19-21. 
     In some embodiments, the delivery system  106  can provide feedback regarding the segment of users that fit within the custom segment as a content provider selects user characteristics and user characteristic values. This feedback can be in the form of a percentage of the users and/or total number of users included in the custom segment. In some configurations, the feedback can be a visual representation of the segment of the user population to which the custom targeted segment would apply. Other methods of providing feedback are also possible. This feedback can aid a content provider in creating a custom segment that precisely meets their needs. 
     Once the delivery system  106  identifies the collection of characteristic values, the delivery system  106  defines at least one custom segment at the content delivery system  106  specifying at least the collection of characteristic values ( 2904 ). 
     In some embodiments, the delivery system  106  can combine the one or more characteristics through the use of one or more Boolean operators, such as AND, OR, or NOT. The Boolean operator can be applied to the user characteristics and/or the user characteristic values. For example, a custom targeted segment could specify the gender characteristic AND the age characteristic. In this case, when the delivery system  106  uses the custom targeted segment for content delivery, the delivery system  106  will only deliver content associated with this segment to users that satisfy both the gender and age requirements. As a second example, a custom targeted segment can specify a location characteristic. Associated with that characteristic the custom segment can specify two user characteristic values: a particular home designated market area and NOT a particular home zip code. In this case, when the delivery system  106  uses the custom targeted segment for content delivery, the delivery system  106  will deliver content associated with the targeted segment to users with characteristic values that match the home designated market area specified in the custom segment unless their home zip code characteristic value matches the home zip code value specified in the custom segment. 
     In some embodiments, the delivery system  106  can assign a weight to one or more user characteristics and/or user characteristic values. For example, a characteristic and/or characteristic value can be assigned a weight in the range [0, 1], where 0 indicates no weight and 1 indicates full weight. Other relative scales can also be used. In some configurations, weights can be used to indicate that the delivery system  106  can present invitational content associated with the custom targeted segment even if the rule is not fully satisfied, so long as the characteristics and/or characteristic values with higher weight are satisfied. 
     In some embodiments, the delivery system  106  can assign an identifier to the custom targeted segment. In some configurations, the content provider who created the custom targeted segment can supply the identifier. For example, in a system configured with a GUI, the GUI can include an input box for the purpose of naming the segment. Alternatively, the UI and UI module  111  can include a save option that prompts the user for a segment name as part of the saving process. Other methods of receiving an identifier from the content provider are possible. In some configurations, the UI and UI module  111  can automatically create an identifier for the custom segment. For example, the identifier can be based on the name of the content provider. 
     In some embodiments, the delivery system  106  can assign a weight to the custom targeted segment. As described above, a variety of scales can be used to assign a weight. In some configurations, weights can be used to indicate that when more than one segment can be used to deliver invitational content, content associated with the segment with a higher weight should be selected first. The weight can be used for other purposes as well. 
     In some configurations, the segment identifier can be used to identify the segment at a later time. In some embodiments, the delivery system  106  saves the custom targeted segment to a storage location such as the segment database  114 . By saving the custom targeted segment, the delivery system  106  can use the segment at a later point to identify targeted content to present to a user. In some configurations, the segment identifier can be used to locate the saved custom targeted segment. However, the delivery system  106  can use the custom targeted segment to select invitational content without saving the segment. 
     Finally, the delivery system  106  books an electronic campaign with the content delivery system comprising at least one inventory slot from the inventory space, wherein the inventory slot is defined in the booked electronic campaign based on at least the custom segment ( 2906 ). The booking step can include associating one or more items of invitational content with the custom segment and/or specifying a campaign goal. 
     In some embodiments, as part of the booking step, the delivery system  106  can associate one or more content providers with the custom targeted segment. In some configurations, the delivery system  106  can associate a single content provider with a custom targeted segment. In this case, only the single associated content provider can use the segment to deliver targeted content. In other configurations, the delivery system  106  can associate any number of content providers with the custom targeted segment, and thus, any of the associated content providers can use the custom targeted segment to deliver targeted content to a user. 
     In some configurations, as part of the booking step, the delivery system  106  can identify all of the target users that fit with the custom targeted segment. Based on this identification the delivery system  106  can assign the user to the custom segment and/or select targeted content to deliver to the users. 
       FIG. 30  illustrates an exemplary graphical user interface (GUI)  3000  for generating a custom segment. The GUI  3000  includes 4 tabbed panels, i.e. demographics, preferences, spend levels, and frequency; each presenting a particular category of user characteristics. The panel selected in this example is the demographics panel  3002 . In this case, the collection of available user characteristics includes: age group, gender, income, ethnicity, life stage, and marital status, which are each presented with an associated check box. To include a characteristic in the custom segment, a content provider simply selects the associated box. Additionally, each characteristic is presented with an expandable list of available user characteristic values. For example, the gender characteristic can be expanded to permit the selection of male and/or female values. This makes it possible for a content provider to create a custom segment that targets users with particular user characteristic values, e.g. only male users or only female users. The GUI  3000  also includes an input box  3004  that can be used to assign an identifier, i.e. a name, to the custom targeted segment. Finally, the GUI  3000  includes a create button  3006  to finalize the process of creating the custom targeted segment. 
     In some embodiments, the delivery system  106  is configured to assign users to a targeted segment of the user population. Accordingly, a segment assigner module  124  can be provided for performing the assignments. The delivery system  106  can also include a segment database  114  that stores previously defined targeted segments. The previously defined targeted segments can be based on channel, demographic, behavioral, and/or spatial-temporal characteristics. The definition of a targeted segment can include one or more user characteristics. For example, a targeted segment can be defined to target a segment of the population shaped by gender and age. Additionally, a user characteristic value for a characteristic can be a single value, multiple values, a range of values, multiple ranges of values, or any combination thereof. For example, for the age characteristic, acceptable values include 19; 19-24; 25-29; etc. In some embodiments, a user characteristic value can be a wildcard value, which indicates that any value is an acceptable match for the user characteristic. 
     Having defined segments to work with, the assigner module  124  can analyze one or more user characteristic values and one or more targeted segment definitions to determine if the user fits within a population segment defined by a targeted segment. The delivery system  106  can then use the segment assignments to select invitational content targeted at the assigned segment to send to the user. 
       FIG. 31  is a flowchart illustrating steps in an exemplary method  3100  for selecting invitational content to send to the user based on demographic segmentation. For the sake of clarity, this method is discussed in terms of an exemplary system such as is shown in  FIG. 1 . Although specific steps are shown in  FIG. 31 , in other embodiments a method can have more or less steps than shown. When a request for content is received, the delivery system  106  delivers invitational content targeted to a user based on an association between the user and a first segment ( 3102 ). 
     After delivering invitational content, the delivery system evaluates feedback descriptive of the user&#39;s interaction with the invitational content targeted to the user ( 3104 ). This feedback can include any information regarding the user&#39;s interaction with the content such as whether the user clicked on any links; how long the user interacted with the content; whether the user completed the associated conversion action; if the user did not complete a conversion, where on the conversion continuum the user abandoned the process, etc. Information regarding the user&#39;s interaction with the content can also include a user&#39;s depth of interaction with the targeted content i.e., how far into the targeted content the user navigated, which is a measure of the quality of the user&#39;s interaction. Such feedback can be used to infer user characteristics, interests and a user&#39;s present context. 
     Periodically, the delivery system  106  analyzes at least one characteristic within a profile associated with the user, the profile being a record of characteristics associated with the user ( 3106 ). In some embodiments, the delivery system  106  can include a user profile database  120 . A user profile can include information descriptive of the user and/or the user&#39;s interaction with various items of content including purchased content. In this case, the delivery system  106  can fetch the user profile from the user profile database  120  and then select the characteristics from the user profile. In some embodiments, the delivery system  106  can determine the at least one characteristic in real-time based on the identified user&#39;s activities during the current session. Alternatively, the at least one characteristic can be included with the request for an item of invitational content. 
     In some cases, one or more user characteristic values used define a targeted segment of the population of users is uncertain. To address this issue, the delivery system  106  can infer/derive the value from trusted values. The delivery system  106  can use the derivation method  3100  described in  FIG. 31  above or any other method to infer/derive the uncertain value. The delivery system  106  can also use other user characteristic values to infer unknown characteristic values. 
     As part of the derivation method, the delivery system  106  can assign a confidence score to the derived value, where the confidence score represents the likelihood that the particular characteristic is valid and/or correct. For example, a characteristic can be assigned a value in the range [0,1], where 0 indicates no confidence and 1 indicates full confidence. Other relative indicators of confidence can also be used such as a percentage. As described above, the calculation of the confidence score can depend on the user characteristic, how the characteristic is obtained, the number of characteristics considered, the number of users considered, etc. 
     After analyzing the at least one characteristic, the delivery system  106  assigns the user into a second segment based on the feedback and at least one user characteristic, the second segment being a grouping of users that share a degree of commonality with respect to their interaction with the invitational content targeted to the user ( 3108 ). The segment assigner module  124  can assign the user to a targeted segment based on the user characteristic values. In some cases, a characteristic value can have an associated confidence score and the system  106  can be configured to only use characteristic values that exceed a specified threshold when assigning a user to a targeted segment. In some configurations, the delivery system  106  can assign a confidence score to the targeted segment assignment. In this case, any confidence scores associated with any user characteristic values can be factored into the confidence score for the segment assignment. In some embodiments, the delivery system  106  can use the segment assignment confidence score in determining whether the segment should be used in selecting invitational content for the user. For example, if the confidence score is below a specified threshold, the delivery system  106  may not use the segment assignment for selecting invitational content. The delivery system  106  can update the user profile database  120  to reflect the segment assignments. 
     Finally, the delivery system  106  targets additional invitational content to the user based on their assignment to the second segment ( 3110 ). In some embodiments, a content provider can associate one or more items of invitational content with the targeted segment associated with the inferred value. The delivery system can then select from the items of invitational content associated with the targeted segment. 
     In some embodiments, the methods illustrated in  FIG. 8-28  can be used to infer one or more demographic values. These inferred demographic values can serve as the bases for one or more targeted segments and can be used to target invitational content to the identified user. 
     In some embodiments, method  3100  is performed only when the delivery system  106  receives a request for invitational content. In other configurations, the delivery system  106  can monitor the user characteristics associated with one or more users. When one or more values changes, the system can re-infer and re-assign the one or more users to targeted segments. For example, for a period of time the user might purchase all of their music from the Jazz category. Based on this contextual characteristic, the user might be assigned to a segment that targets Jazz listeners. At some later period, the user might begin to purchase music from the Blues category. These purchases will alter the value for the recent purchase frequency characteristic. When this occurs, the system  106  can re-analyze the set of user characteristics against the one or more rules. Based on the new analysis, the system  106  can update the segments to which the user is assigned. In this example, the user may no longer be assigned to the segment that targets Jazz listeners. In some configurations, the delivery system  106  can periodically re-infer and re-assign the users to targeted segments. 
       FIG. 32  is a flowchart illustrating steps in an exemplary method  3200  for assigning a user to a behavioral targeted segment and using the segment assignment to select invitational content to send to the user. For the sake of clarity, this method is discussed in terms of an exemplary system such as is shown in  FIG. 1 . Although specific steps are shown in  FIG. 32 , in other embodiments a method can have more or less steps than shown. 
     First, the delivery system  106  analyzes user characteristic data related to an identified user for behavioral patterns ( 3202 ). Behavioral patterns that can be identified based on the user characteristic data include for example patterns that can indicate a user&#39;s present or long-term intent or interest. Some examples include identifying the users propensity to convert or click on an item of invitational content; identifying when a user is about to, or is traveling; identifying when a user is researching a product or content, etc. From the analysis of the user characteristic data the system can infer interests in various products or user intent ( 3204 ) and categorize the user into a behavioral segment representative of that interest or intent ( 3206 ). 
     The analyzing step can be conducted using one or more rules, of which some examples are below, but in some embodiments, machine learning algorithms, and predictive algorithms can be used to predict user intents and interests. 
     In some embodiment classifying algorithms can be used for the behavioral segmentation. The following are several descriptive examples of such: 
     Cross-channel Mavens—users that access content on a cellular network, wireless network, and wired network in the same session more than 3 times per week. 
     Affluentials—users are both affluent and influential—that have a household income greater than $120,000 and that complete more than 3 conversions per week. 
     Money and Brains—users that have a household income greater than $150,000 and that interact with financial and technology content in more than 10 sessions per week. 
     Comfort Zone—users that interacted with content from their home location less than an hour ago and the user performed a search for local content in the past hour. 
     Out of Comfort Zone—users that interacted with content from a location that is not their home location less than an hour ago and searched for travel content in the past hour. 
     InTransit—users that interact with content from more than one location in a single session. 
     Home Based—users that interact with content from their home location. 
     Biz Traveler—users that interact with content from more than 5 locations in a single month and interact with content from a private Internet Protocol address. 
     Leisure Travel—users that interact with content from a resort location and search for local content from a location outside of their home location. 
     Heavy Sports User—users where more than 80% of the content they interact with via a cellular or wireless network is sports content and the user spends more than 4 minutes per day interacting with sports content. 
     Converter or Click Lookalikes—users that matches the behavior pattern of a user who has completed the associated conversion action for the content. 
     Gizmo Geek—users that have more than 5 page views on technology sites and 4 utility applications and clicked on mobile site and targeted laptop product category in last 5 days. 
     Auto Enthusiast—users that have more than 5 page views on auto sites in the past 14 days. 
     Globetrotters—users that consistently have an observed location greater than 1000 miles from their home location every 2 months. 
     Affluent Auto Intender—users that have a household income greater than $120,000, have interacted with auto sites in more than 10 sessions in the past 5 days, and optionally have viewed auto reviews and/or auto videos. 
     Social Butterflies—users that interact with a social networking application more than 5 times in a single day. 
     Entertainment Buffs targeted segment—users that have more than 5 page views on entertainment sites in a week, more than 3 video applications, and more than 70% of cellular network usage is video or more than 4 music purchases per week. 
     Deal Follower targeted segment—defined to target users that are in transit and whose location is equal distance from two competitive retail locations. 
     Tween Device Persona—users that use portable multimedia player devices that are not connected to a cellular network. 
     As evident from many of the targeted segments identified above, real-time or at least frequently refreshed user characteristic data is used to assign users to these segments. In such instances, the data can be discarded after the user has been classified into the segments. In some embodiments purging some data also serves the benefit of needing to store less sensitive information about a user. Such purging is not only useful with respect to behavioral data, but can also be used with respect to recording user characteristics (which can themselves be derived from some real time data) or any other segmentation. Once the data is used to identify the sought after characteristics it can be discarded because it is no longer needed. 
     As may be evident from the above discussion, a user can potentially be grouped into many segments and thus eligible to receive targeted content for each of those segments. However, some segments can be more important or valuable or have more content than others. In some embodiments, the delivery system  106  is configured to create a prioritized list of targeted segments assigned to a user. Accordingly, a segment prioritizing module  128  can be provided for performing the prioritization. The prioritizing module  128  can be configured to take a list of targeted segments and order the list based on a specified goal. In some cases, the specified goal can be a campaign goal provided by a content provider and/or an optimization. 
       FIG. 33  is a flowchart illustrating steps in an exemplary method  3300  for prioritizing segments assigned to a user. For the sake of clarity, this method is discussed in terms of an exemplary system such as is shown in  FIG. 1 . Although specific steps are shown in  FIG. 33 , in other embodiments a method can have more or less steps than shown. First, the content delivery system  106  identifies one or more targeted segments associated with the user ( 3302 ). In some cases, the delivery system  106  can assign the user to one or more targeted segments based on an analysis of the user characteristics and the targeted segments maintained by the delivery system  106 . The delivery system  106  can use methods  3100  in  FIGS. 31 and 3200  in  FIG. 32  in the segment assignment or any other segment assignment methods. In some embodiments, the delivery system  106  may have already performed the segment assignments and the assignments are stored in the user profile in the user profile database  120 . 
     Next, the delivery system  106  prioritizes the one or more targeted segments based on a specified goal, the goal associating a targeted segment with a target objective ( 3304 ). The goal can be specified by a content provider and/or the delivery system  106 . In some embodiments, a campaign goal can specify one or more targeted segments and a target objective. The target objective can be expressed in several ways. For example, the target objective can specify a maximum budget not to be exceeded. In another example, the target objective can specify a budget that varies based on segment. That is, different cost objectives can be specified for different targeted segments. Additionally, other types of target objects can also be used. For example, these can include performance metrics, such as click-through rate (CTR), an effective cost per thousand impressions (eCPM), a target conversion rate, a target fill rate, user engagement, to name a few. Further, any combination of target objectives can be used in the present technology. For example, a target objective can specify both CTR and eCPM. 
     The prioritizing module  128  can analyze the list of targeted segments assigned to a user and determine the ideal ordering of those segments with respect to the associated target objective. In some embodiments, the prioritizing module  128  can perform the analysis based on characteristics of the user. The prioritizing module  128  can obtain these characteristics in a number of ways. In some cases, the characteristics can be stored in the user profile database  120 , which the prioritizing module  128  can access. The characteristics can also be provided as part of the request to perform the prioritization. 
     In some configurations, the delivery system  106  considers the user&#39;s context in ranking the assigned segments. In this case, the delivery system  106  ranks higher those segments that are more relevant to the user&#39;s current context. For example, if the delivery system  106  detects that the user is traveling, then the delivery system  106  will rank travel related segments higher. 
     In some configurations, the delivery system  106  makes a prediction as to the level of interest of the user with respect to one or more items of invitational content. In this case, the delivery system  106  ranks higher those segments that are more likely to be of interest to the user. For example, if the delivery system  106  detects that the user is more likely to be interested in content offered by one rental car company rather than another, segments associated with that content will be ranked higher. 
     In some configurations, the delivery system  106  can rank the segments considering both context and level of interest. In this case, a segment might have a high ranking when considering the user&#39;s content, but end up with a lower ranking because the level of interest is low. For example, if the delivery system  106  detects that the user is traveling, the delivery system  106  can rank rental car content high, but content from a particular car rental company can be ranked lower in the list because the user is unlikely to be interested in the content. In some cases, one or more segments that are assigned to the user will not be ranked because the content is not applicable to the context, the user is unlikely to be interested, there is not content applicable to the current campaign goals, etc. 
     In the case where a campaign goal specifies more than one target objective, the prioritizing module  128  can integrate the one or more target objectives in the prioritization to create a balance between the objectives. For example, one objective could be to maximize CTR while a second could be to minimize cost. In some configurations, a weight can be assigned to the target objectives and the weights can be considered when integrating the one or more target objectives. 
     The segment prioritization can occur at various times. For example, the delivery system  106  can be configured to trigger the prioritizing module  128  at specified intervals. Alternatively, the prioritizing module  128  can order the segments when the delivery system  106  receives a request for invitational content. In some configurations, the prioritizing module  128  can monitor the user characteristics and/or target objective and perform the prioritization when a change in the user characteristics and/or target objective is detected. 
     In some configurations, a campaign goal can additionally specify a match criteria for the one or more segments specified in the goal. That is, for at least one of the targeted segments in the goal, the goal can include acceptable variations in the user characteristic identifiers and/or user characteristic values. For example, the goal can specify a targeted segment with a location user characteristic and the city of San Francisco as the user characteristic value. The associated match criteria can specify a user characteristic value of northern California for the location user characteristic identifier. Such a match criteria can make it possible to match the goal with a greater number of targeted segments. 
     After prioritizing the segments, the delivery system  106  can use the ordered list to aid in selecting invitational content to deliver to the user. To illustrate, suppose a user is assigned to segments a, b, c, and d and the associated target objective for these segments is to maximize the CTR. After analyzing the characteristics of the user, the prioritizing module  128  determines the user is most likely to click through on content related to segment c followed by b, d, and a. When the delivery system  106  receives a request for invitational content for the user, the delivery system  106  will first attempt to deliver content associated with segment c. If no content exists for segment c, the delivery system  106  will go down the prioritized list and pick content associated with the next best segment. 
       FIG. 34  illustrates an exemplary segment assignment prioritization process  3400 . In this example, User  3422123  is assigned to 8 segments ( 3402 ). The prioritizing module takes these 8 segments along with their associated campaign goals and ranks the segments in a manner that optimizes the campaign goals ( 3404 ). It should be noted that in this example, that the user was assigned to 8 segments, but after prioritizing the segments only a subset of the segments are currently used for targeting content. As mentioned above, the user&#39;s context and the currently available content/campaign goals are used in determining the prioritization. In this case, a couple of the segments were not applicable to the user&#39;s context and/or the campaign goals. 
     Also factoring into the segment prioritization scheme is a predictive performance module, which predicts the effect of prioritizing one segment over another and how it can affect other system priorities. For example if the segments are being ordered to ensure that each item of invitational content is interacted with a specified number of times, the predictive performance module can run a variety of virtual “what if scenario” models to predict if a particular prioritization of segments will achieve the systems goals. In one example of how this can work, if the goal is to get five clicks on targeted content directed to rental cars from two competitor companies, the predictive performance module will rule out any ordering of segments that will always provide targeted content from one company before the other because it will reduce the likelihood that the second item of invitational content presented to the user will be clicked on. Accordingly, the predictive performance module would select a different ordering of segments and ultimately choose the best ordering to optimize the system to meet its goals. 
     With reference to  FIG. 35 , an exemplary system  3500  includes a general-purpose computing device  3500 , including a processing unit (CPU or processor)  3520  and a system bus  3510  that couples various system components including the system memory  3530  such as read only memory (ROM)  3540  and random access memory (RAM)  3550  to the processor  3520 . The system  3500  can include a cache  3522  of high speed memory connected directly with, in close proximity to, or integrated as part of the processor  3520 . The system  3500  copies data from the memory  3530  and/or the storage device  3560  to the cache  3522  for quick access by the processor  3520 . In this way, the cache  3522  provides a performance boost that avoids processor  3520  delays while waiting for data. These and other modules can be configured to control the processor  3520  to perform various actions. Other system memory  3530  may be available for use as well. The memory  3530  can include multiple different types of memory with different performance characteristics. It can be appreciated that the disclosure may operate on a computing device  3500  with more than one processor  3520  or on a group or cluster of computing devices networked together to provide greater processing capability. The processor  3520  can include any general purpose processor and a hardware module or software module, such as module  1   3562 , module  2   3564 , and module  3   3566  stored in storage device  3560 , configured to control the processor  3520  as well as a special-purpose processor where software instructions are incorporated into the actual processor design. The processor  3520  may essentially be a completely self-contained computing system, containing multiple cores or processors, a bus, memory controller, cache, etc. A multi-core processor may be symmetric or asymmetric. 
     The system bus  3510  may be any of several types of bus structures including a memory bus or memory controller, a peripheral bus, and a local bus using any of a variety of bus architectures. A basic input/output (BIOS) stored in ROM  3540  or the like, may provide the basic routine that helps to transfer information between elements within the computing device  3500 , such as during start-up. The computing device  3500  further includes storage devices  3560  such as a hard disk drive, a magnetic disk drive, an optical disk drive, tape drive or the like. The storage device  3560  can include software modules  3562 ,  3564 ,  3566  for controlling the processor  3520 . Other hardware or software modules are contemplated. The storage device  3560  is connected to the system bus  3510  by a drive interface. The drives and the associated computer readable storage media provide nonvolatile storage of computer readable instructions, data structures, program modules and other data for the computing device  3500 . In one aspect, a hardware module that performs a particular function includes the software component stored in a non-transitory computer-readable medium in connection with the necessary hardware components, such as the processor  3520 , bus  3510 , display  3570 , and so forth, to carry out the function. The basic components are known to those of skill in the art and appropriate variations are contemplated depending on the type of device, such as whether the device  3500  is a small, handheld computing device, a desktop computer, or a computer server. 
     Although the exemplary embodiment described herein employs the hard disk  3560 , it should be appreciated by those skilled in the art that other types of computer readable media which can store data that are accessible by a computer, such as magnetic cassettes, flash memory cards, digital versatile disks, cartridges, random access memories (RAMs)  3550 , read only memory (ROM)  3540 , a cable or wireless signal containing a bit stream and the like, may also be used in the exemplary operating environment. Non-transitory computer-readable storage media expressly exclude media such as energy, carrier signals, electromagnetic waves, and signals per se. 
     To enable user interaction with the computing device  3500 , an input device  3590  represents any number of input mechanisms, such as a microphone for speech, a touch-sensitive screen for gesture or graphical input, keyboard, mouse, motion input, speech and so forth. An output device  3570  can also be one or more of a number of output mechanisms known to those of skill in the art. In some instances, multimodal systems enable a user to provide multiple types of input to communicate with the computing device  3500 . The communications interface  3580  generally governs and manages the user input and system output. There is no restriction on operating on any particular hardware arrangement and therefore the basic features here may easily be substituted for improved hardware or firmware arrangements as they are developed. 
     For clarity of explanation, the illustrative system embodiment is presented as including individual functional blocks including functional blocks labeled as a “processor” or processor  3520 . The functions these blocks represent may be provided through the use of either shared or dedicated hardware, including, but not limited to, hardware capable of executing software and hardware, such as a processor  3520 , that is purpose-built to operate as an equivalent to software executing on a general purpose processor. For example the functions of one or more processors presented in  FIG. 35  may be provided by a single shared processor or multiple processors. (Use of the term “processor” should not be construed to refer exclusively to hardware capable of executing software.) Illustrative embodiments may include microprocessor and/or digital signal processor (DSP) hardware, read-only memory (ROM)  3540  for storing software performing the operations discussed below, and random access memory (RAM)  3550  for storing results. Very large scale integration (VLSI) hardware embodiments, as well as custom VLSI circuitry in combination with a general purpose DSP circuit, may also be provided. 
     The logical operations of the various embodiments are implemented as: (1) a sequence of computer implemented steps, operations, or procedures running on a programmable circuit within a general use computer, (2) a sequence of computer implemented steps, operations, or procedures running on a specific-use programmable circuit; and/or ( 3 ) interconnected machine modules or program engines within the programmable circuits. The system  3500  shown in  FIG. 35  can practice all or part of the recited methods, can be a part of the recited systems, and/or can operate according to instructions in the recited non-transitory computer-readable storage media. Such logical operations can be implemented as modules configured to control the processor  3520  to perform particular functions according to the programming of the module. For example,  FIG. 35  illustrates three modules Mod 1   3562 , Mod 2   3564  and Mod 3   3566  which are modules controlling the processor  3520  to perform particular steps or a series of steps. These modules may be stored on the storage device  3560  and loaded into RAM  3550  or memory  3530  at runtime or may be stored as would be known in the art in other computer-readable memory locations. 
     Embodiments within the scope of the present disclosure may also include tangible and/or non-transitory computer-readable storage media for carrying or having computer-executable instructions or data structures stored thereon. Such non-transitory computer-readable storage media can be any available media that can be accessed by a general purpose or special purpose computer, including the functional design of any special purpose processor as discussed above. By way of example, and not limitation, such non-transitory computer-readable media can include RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium which can be used to carry or store desired program code means in the form of computer-executable instructions, data structures, or processor chip design. When information is transferred or provided over a network or another communications connection (either hardwired, wireless, or combination thereof) to a computer, the computer properly views the connection as a computer-readable medium. Thus, any such connection is properly termed a computer-readable medium. Combinations of the above should also be included within the scope of the computer-readable media. 
     Computer-executable instructions include, for example, instructions and data which cause a general purpose computer, special purpose computer, or special purpose processing device to perform a certain function or group of functions. Computer-executable instructions also include program modules that are executed by computers in stand-alone or network environments. Generally, program modules include routines, programs, components, data structures, objects, and the functions inherent in the design of special-purpose processors, etc. that perform particular tasks or implement particular abstract data types. Computer-executable instructions, associated data structures, and program modules represent examples of the program code means for executing steps of the methods disclosed herein. The particular sequence of such executable instructions or associated data structures represents examples of corresponding acts for implementing the functions described in such steps. 
     Those of skill in the art will appreciate that other embodiments of the disclosure may be practiced in network computing environments with many types of computer system configurations, including personal computers, hand-held devices, multi-processor systems, microprocessor-based or programmable consumer electronics, network PCs, minicomputers, mainframe computers, and the like. Embodiments may also be practiced in distributed computing environments where tasks are performed by local and remote processing devices that are linked (either by hardwired links, wireless links, or by a combination thereof) through a communications network. In a distributed computing environment, program modules may be located in both local and remote memory storage devices. 
     The various embodiments described above are provided by way of illustration only and should not be construed to limit the scope of the disclosure. Those skilled in the art will readily recognize various modifications and changes that may be made to the principles described herein without following the example embodiments and applications illustrated and described herein, and without departing from the spirit and scope of the disclosure.