Patent Publication Number: US-7903790-B2

Title: System and method for completing incomplete records in a database of twisted cable pair information

Description:
RELATED APPLICATION 
     This application is a continuation of U.S. patent application Ser. No. 10/382,182 filed Mar. 5, 2003 now U.S. Pat. No. 7,079,626, the content of which is hereby incorporated in its entirety by reference. 
    
    
     TECHNICAL FIELD OF THE INVENTION 
     The present invention relates generally to information processing, and more specifically relates to a system and method for imputing data into a database. 
     BACKGROUND OF THE INVENTION 
     In a telephone network, a telephone loop is the wired connection from a telephone company&#39;s central office in a city to the residences and businesses of the customers. The central office includes switching equipment that switches telephone calls locally or to long-distance carrier telephone offices. Typically each city has its own telephone central office and each central office includes one or more wire centers where the number of wire centers depends on the number of customers or subscribers in the city. The telephone loop consists of one or more segments of twisted pair copper wires spliced together and was originally designed for voice transmissions on a single voice channel. 
     DSL Internet services allow residential and business customers to receive broadband Internet services over the telephone loop of the telephone network. But in order to receive DSL services, the residences and businesses must be within a certain distance of the telephone company&#39;s central office, and the twisted pair of copper wire must be of a particular gauge. Therefore the telephone companies must keep accurate records regarding wire gauge and the distances from the central office to residences and businesses, so that when a customer requests DSL service, the telephone company will be able to quickly determine if the customer is within the required distance and therefore eligible to receive DSL service. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A more complete understanding of the present embodiments and advantages thereof may be acquired by referring to the following description taken in conjunction with the accompanying drawings, in which like reference numbers indicate like features, and wherein: 
         FIG. 1  depicts an example telephone loop; 
         FIG. 2  illustrates a block diagram of an example system for imputing missing data; and 
         FIG. 3  depicts a flow diagram of an example embodiment of a method for imputing missing data. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Preferred embodiments of the present invention are illustrated in the figures, like numerals being used to refer to like and corresponding parts of the various drawings. 
     The telephone copper loop network consisting of twisted pair copper wire has evolved from providing only voice to providing digital services such as Digital Subscriber Line (“DSL”) services. Telephone companies keep and maintain numerous databases that store various information regarding the telephone loop. One such database is the Loop Facility Assignment System (“LFACS”) database which contains elements that are used to form the basic access method to the telephone network. The LFACS database includes information regarding the layout of the telephone loop and characteristics of the telephone loop such as lengths of cable runs and the gauge of the cable. 
     As more home and business users request and require broadband Internet access such as DSL over the telephone loop, the telephone companies and service provider companies that provide DSL services need a way to quickly scan the various databases such as LFACS and extract information in order to qualify customers for DSL. Unlike POTS (“Plain Old Telephone Service”) where any loop engineered to resistance design rules can be used to provide voice services to customers, DSL requires knowledge about the lengths and gauges of the wire that makes up the loop. Incomplete information in the LFACS database creates lost revenue for the telephone companies and service provider companies due to the loss of qualified customers who cannot be qualified due to missing data. Furthermore, inaccurate information on telephone loop makeup involves additional revenue loss in attempting to provide DSL service to customers over a loop which does not qualify for DSL. 
     The telephone loop is the basic copper wire pair that connects a subscriber living unit (either a residence or a business) to a wire center located within a central office. Telephone loops are typically composed of two segments: a feeder segment and a distribution segment. The feeder segment comprises the majority of the length of the loop and runs from the wire center to a BBox while the distribution segment comprises the minority of the loop&#39;s overall length but can still exceed three or four thousand feet in length and travels from the BBox to one or more serving terminals. In order to provide basic telephone voice service, the POTS network does not require detailed knowledge of the distribution segment such as the length of the distribution segment and the gauge of the wire or cable in the distribution segment. Therefore, details regarding the distribution segment were not recorded by outside plant construction when the telephone loop was created and installed. Detailed information regarding the distribution segment was entered in the LFACS database only when special circuits required detailed loop information. Length and gauge information was rendered through examination of outside plant construction detail maps or electrical measurements such as taken with time-domain reflectometers or capacitative looplength instrumentation. 
     DSL, a mass-market service, requires detailed information regarding the distribution segment in order to determine if customers are eligible to receive DSL services. But many of the loops that may qualify for DSL service are missing information regarding the distribution segment in the LFACS database. Therefore when a customer calls requesting DSL and information for the distribution segment serving that customer is missing from the LFACS database, the company has two options: refuse to qualify the customer for DSL service due to the missing data or send a company technician to the customer site to determine if the customer is eligible for DSL and install DSL if the customer is eligible. Both of these options result in lost revenue for the company and dissatisfied customers. If the company refuses to qualify the customer, the customer may become dissatisfied with the company. Furthermore, if the customer is actually eligible for DSL, the company has lost out on a potential revenue source. If the company sends out a technician to determine DSL status and install DSL if eligible, the company wastes money on the technician visit if the customer is not eligible for DSL and the customer is unsatisfied with the company because the company told the customer he could get DSL and now the customer cannot get DSL. 
     In order to avoid the above problems, service providers and telephone companies have developed ways to estimate distribution segment data when it is missing from a company database. One such method is segregating the outside plant records by a digital area or tapercode. The tapercode is contained in the LFACS database and indicates a distribution area. Feeder segment and distribution segment cables are brought together for splicing to a location called a BBox, the BBox serving a tapercode. The telephone company uses the longest distribution cable found in the tapercode as the estimator for missing distribution segments. The problem with this approach is that a tapercode typically includes a wide variety of segment lengths, and selecting the longest of these cable lengths results in biasing the estimation towards longer lengths, which prevents customers who are eligible for DSL from qualifying, resulting in lost revenue to the telephone company and dissatisfied customers. 
     In addition, a mechanized loop test (“MLT”) can be used to measure segments within the loop. The MLT performs a capacitive length measurement of the loop but, being a subsystem of the electronic switching system, it can measure only the lengths of loops of working telephone numbers. Therefore, MLT does not provide any useful data for new customers desiring to set up both a new telephone line and DSL service. Furthermore, telephone companies may estimate the length and gauge of the distribution segment by looking at street addresses and DSL service records and not by looking at the actual data in the LFACS database. The telephone companies assume that if a neighbor of a customer requesting DSL is eligible for DSL, then the customer must also be eligible. But this can lead to dissatisfied customers and money wasted on technician calls when the technician goes to install DSL and determines that the customer is not eligible. 
     By contrast, the example embodiment described herein allows for the estimation and imputing of missing data into a database utilizing outside plant construction principles. This results in consistent and more accurate imputed data. Because outside plant construction principles are utilized to impute the data, the resulting imputed data is more accurate and a better estimation of the actual data. Revenue is created because the imputed data is of greater accuracy allowing for more customers to be qualified for DSL service where before they would have been refused due to missing data. Time and money is saved because technician visits are required less often to determine DSL qualification status when there is missing data. In addition, customers experience a greater satisfaction level due to the ability to receive DSL service and not be denied DSL service when initially told that they are eligible. 
     Referring now to  FIG. 1 , an example telephone network  10  is shown imposed over a street map in a typical distribution area. Telephone network  10  includes loops  11  and  13 , wire center  12 , BBox  14 , serving terminals  16 ,  18 ,  20 ,  22 ,  24 ,  26 ,  28 ,  30 ,  32 ,  34 , and  36 , feeder cable  37 , and distribution cable  38 . Although telephone network  10  is shown with one wire center, one BBox, two loops, eleven serving terminals, one feeder cable, and one distribution cable, in alternate embodiments telephone network  10  may include more than one wire center, more than one BBox, more or less than two loops, more or less than sixteen serving terminals, more than one feeder cable, and more than one distribution cable. Furthermore, wire center  12  may be disposed within a central office that includes more than one wire center. 
     When the telephone company constructs telephone network  10 , the telephone company employs the outside plant construction practice of constructing the twisted pair telephone wire or cable in binder group pairs such as 5-pair, 25-pair, and 100-pair binder groups. When the telephony cable is manufactured, the pairs are counted off in groups of five and then wound with a marker, such as a plastic ribbon, which allows the outside plant personnel to handle the pairs as a unit. Five 5-pair binder groups are combined into a 25-pair binder group separated by wrapping with a ribbon. Likewise, four 25-pair binder groups are wrapped such that they form a 100-pair binder group. Furthermore, 100-pair binder groups may be wrapped together to further form any appropriate binder group size such as 200-pair, 300-pair, or 500-pair binder groups. 
     As the cable is laid out in telephone network  10 , the cable pairs tend to remain grouped until there is a reason to separate them. For instance, an 800-pair distribution cable  38  may be laid along a busy thoroughfare starting at BBox  14 , thereby creating loops  11  and  13 . As cross streets containing residences or businesses are passed, one or more  25 -pair binder groups will be separated from the main cable and laid down the cross streets. As the binder group travels along the street, serving terminals are built every few houses and some of the pairs in the 25-pair binder group are terminated at a serving terminal. For example, feeder cable  37  originates at wire center  12  and traverses along Jefferson and Anderson to cross connection terminal BBox  14 . At BBox  14 , feeder cable  37  is cross-connected to the distribution cable  38 . From BBox  14 , distribution cable  38  takes different directions with distribution cable  38   a  including 100-pair binder group pair numbers  0 -  99  traversing Olive to Main to form loop  11 , and distribution cable  38   b  including 125-pair binder group pair numbers  100 - 224  traversing Olive to Maple to form loop  13 . BBox  14  and distribution cable  38   a  including cable pair numbers  0 - 99  service five serving terminals  16 ,  18 ,  20 ,  22 , and  24  while BBox  14  and distribution cable  38   b  including cable pair numbers  100 - 224  service six serving terminals  26 ,  28 ,  30 ,  32 ,  34 , and  36 . The remaining 575 cable pairs continue along in the direction of arrow  41  to create additional loops within telephone network  10 . 
     Serving terminals  16 ,  18 ,  20 ,  22 ,  24 ,  26 ,  28 ,  30 ,  32 ,  34 , and  36  are small boxes positioned along the street every few houses with typically six to twenty-five cable pairs terminated at each serving terminal. The six to twenty-five cable pairs are allocated to the five or six residences in the serving terminal&#39;s vicinity on an as needed basis. For instance, distribution cable  38   a  terminates cable pairs at serving terminal  24  that service residences in the vicinity of Yale and Beanna, while distribution cable  38   b  terminates cable pairs at serving terminal  36  that service residences in the vicinity of Maple and Congress. In addition, each serving terminal  16 ,  18 ,  20 ,  22 ,  24 ,  26 ,  28 ,  30 ,  32 ,  34 , and  36  has a serving terminal address which is a physical address where the serving terminal resides. The serving terminal address includes a number and a street name. For instance, serving terminal  18  may have a serving terminal address of 2529 Main, serving terminal  20  may have a serving terminal address of 2775 Main, and serving terminal  26  may have a serving terminal address of 810 Olive. Furthermore, each serving terminal  16 ,  18 ,  20 ,  22 ,  24 ,  26 ,  28 ,  30 ,  32 ,  34 , and  36  is defined within the LFACS database by the serving terminal address. 
     The outside plant construction principles of constructing distribution cable  38  in binder groups of cable pairs and terminating a specified number of cable pairs at each serving terminal allows for serving terminals served by a single cable to have similar distribution segment characteristics such as length of cable from wire center  12  to the serving terminals and the gauge of the cable. For instance, all the cable pairs terminated at serving terminal  20  should be the same distance from wire center  12  and be of similar gauge since the cable pairs from feeder cable  37  and the cable pairs of distribution cable  38  terminated at serving terminal  24  should all be of approximately the same distance from wire center  12  and of similar gauge. In addition, the cable pairs at serving terminals  20  and  24  should be of similar distance from wire center  12  since serving terminals  20  and  24  are located relatively close to each other and of similar gauge since the cable pairs are from the same distribution cable  38 . Furthermore, the cable pairs tend to remain aggregated in their binder groups such that the cable pairs making up loop  11  are likely to be the same distance from wire center  12  and of the same gauge as the other 99-pairs in distribution cable  38   a &#39;s 100-pair binder group. 
     Referring now to  FIG. 2 , a block diagram depicts imputing system  42  for imputing missing data into a database. In the example embodiment, imputing system  42  may include respective software components and hardware components, such as processor  44 , memory  46 , input/output ports  48 , hard disk drive (HDD)  50  containing inventory database  52  and loop database  54 , and those components may work together via bus  56  to provide the desired functionality. The various hardware and software components may also be referred to as processing resources. Imputing system  42  may be a personal computer, a server, or any other appropriate computing device and located at wire center  12 , at a central office, a location remote from wire center  12 , or any other appropriate location. Imputing system  42  also includes data engine  58 , search engine  60 , and loop engine  62 , which reside in memory such as HDD  50  and are executable by processor  44  through bus  56 . 
     In the embodiment shown in  FIG. 2 , imputing system  42  includes inventory database  52  and loop database  54 . Inventory database  52  includes a plurality of feeder records and distribution records for all the cable pairs which are spliced together to form telephone network  10 . Each feeder record includes information regarding the distance and gauge from wire center  12  to BBox  14  as well as distribution records which include information regarding the distance and gauge from the BBox to the serving terminal where the distribution cable pair terminates, including the distance from wire center  12  to the terminating serving terminal. Inventory database  52  is indexed and searchable by serving terminal address. For instance, a user may desire the distribution records for the cable pairs terminating at serving terminal  20 . Therefore, the user searches 2775 Main, the serving terminal address for serving terminal  20 , in inventory database  52  and the search returns the distribution records for the cable pairs terminating at serving terminal  20 . But the distribution records may be incomplete and not include distance or gauge information, include distance but no gauge information, or include gauge but no distance information. In addition, inventory database  52  may also be referred to as the LFACS database. 
     Loop database  54  includes information regarding what cable pairs are associated with what cable numbers and which serving terminals  16 ,  18 ,  20 ,  22 ,  24 ,  26 ,  28 ,  30 ,  32 ,  34 , and  36  the cable pairs terminate. For instance, a search of loop database for cable pair number  30  reveals that cable pair number  30  is part of cable number  03041  and terminates at serving terminal  26 . In alternate embodiments, imputing system  42  may include more than two or less than two databases. 
     Imputing system  42  may further include display  64  for presenting graphical user interface (GUI)  66  and input devices such as a mouse and a keyboard. Display  64  presents GUI  66 , which allows for a user to view the information stored in inventory database  52  and loop database  54 . Shown in  FIG. 2  is an example GUI  66  from inventory database  52  showing the distribution records for the cable pairs terminating at serving terminal  26 . 
       FIG. 3  illustrates a flow diagram of one embodiment of a method for imputing missing data into inventory database  52 . The method begins at step  80  and at step  82  data engine  58  classifies serving terminals  16 - 36  into a known class or an unknown class based on the distribution records for each of the serving terminals. The known class of serving terminals includes serving terminals for which every distribution record for the cable pairs terminated at the serving terminal is known and therefore includes both the distance number and the gauge number. The unknown class of serving terminals includes the serving terminals where at least one of the cable pairs terminating at the serving terminal has a distribution record that includes missing data. For example, serving terminal  26  is classified in the unknown class because the distribution records for the cable pairs terminating at serving terminal  26  include missing data as shown by GUI  66  in  FIG. 2 . 
     Once serving terminals  16 - 36  have been classified, at step  84  the address is acquired from the user who is desiring DSL service and at step  86  data engine  58  determines the corresponding serving terminal and serving terminal address for the user requesting DSL service. For instance, a residential customer may call the telephone company to request DSL service. A customer service representative or an automated system such as an interactive voice response unit queries the customer for the address for which the customer is requesting DSL service. When the customer provides the address, data engine  58  determines which serving terminal serves the location for which the customer is requesting DSL service. For example, if the customer is a residential customer living at 2802 Main and requesting home DSL, then data engine  58  determines that serving terminal  20  serves the customer based on the customer&#39;s address. When data engine  58  determines which serving terminal serves the requesting address, at step  88  search engine  60  searches loop database  54  for the cable and cable pairs that terminate at the desired serving terminal and at step  90  determines which of the cable pairs that terminate at serving terminal  20  serve the customer. 
     When imputing system  42  determines the cable pairs serving the customer requesting DSL service, data engine  58  examines inventory database  52  in order to determine if the distribution record for the desired cable pair includes any missing data. Because inventory database  52  is indexed by serving terminal, data engine  58  examines inventory database  52  for the desired serving terminal serving the customer. Once the desired serving terminal is located, data engine  58  locates the desired distribution record for the desired cable pair serving the customer in order to determine if the distribution record includes both a distance value and a gauge value. For instance, data engine  58  examines inventory database  52  for serving terminal  20  in order to locate the distribution record for the desired cable pair serving the customer requesting DSL service. Once data engine  58  locates the desired cable pair and the associated desired distribution record, at step  94  data engine  58  determines if the desired distribution record is a complete distribution record or if it includes missing data. 
     If at step  94  the desired distribution record for the desired cable pair is a complete distribution record including both the distance value and the gauge value, then at step  96  imputing system  42  determines if the customer qualifies for DSL service based on the complete distribution record. If the distance and gauge values satisfy the required parameters for DSL service, then the customer is eligible for DSL service. But if either the distance value or the gauge value exceeds the required values for DSL service, then the customer does not qualify for DSL service. At step  98  the customer is informed as to whether or not they are eligible for DSL based on the distribution record and the method ends. 
     If at step  94  the desired distribution record is incomplete and therefore does not include the distance value, the gauge value, or both of these values, then at step  102  search engine  60  searches the known class of serving terminals  16 - 36  to determine if the desired cable pair makes an appearance at one of the serving terminals in the known class. Even though the desired cable pair has an incomplete distribution record at the serving terminal at which it terminates, the associated serving terminal, the desired cable pair may make an appearance at another serving terminal at which it does not terminate and therefore is not associated with. For example, a cable pair that terminates at serving terminal  30  passes through serving terminal  28  before terminating at serving terminal  30 . Serving terminal  28  may include the distribution record for the cable pair terminating at serving terminal  30 . If serving terminal  28  is classified in the known class, then when search engine  60  searches the known class for the desired cable pair, search engine  60  will locate a complete distribution record for the desired cable pair at serving terminal  28 . Because the distance between serving terminals  28  and  30  is not excessive and the gauge is unlikely to change between serving terminals  28  and  30 , the distribution record for the desired cable pair located at the serving terminal in the known class is an accurate representation for the distribution record for the desired cable pair terminating at serving terminal  30 . 
     If at step  104  search engine  60  locates a complete distribution record for the desired cable pair at an unassociated serving terminal in the known class, then loop engine  62  imputes the complete distribution record from the unassociated serving terminal in the known class to the desired distribution record for the desired cable pair at step  106 . Once loop engine  62  imputes the values into the desired distribution record, at step  108  loop engine  62  marks the desired distribution record including the imputed data in inventory database  52  as including imputed data and not actual data. Such marking may consist of an asterisk by the distribution record in inventory database  52 , a keycode indicating if the data is actual or imputed and the method used to impute the data, checking a column for imputed data, or any other appropriate way of marking the data as imputed. 
     After the desired distribution record has been marked as including imputed data, the process continues to step  110  where imputing system  42  determines if the customer qualifies for DSL service based on the imputed distribution record. If the imputed distance and/or gauge values are within the required parameters for DSL service, then the customer is eligible for DSL service. But if either of the imputed values for the desired distribution record are outside of the required parameters for DSL service, then the customer does not qualify for DSL service. At step  112  the customer is informed as to whether or not they are eligible for DSL based on the desired distribution record including imputed data. Loop engine  62  then compares the imputed values in the desired distribution record in inventory database  52  with the actual value at step  114 . The actual values for the desired distribution record may be obtained at a time later than when the imputed distribution values are determined. 
     The actual values for distance and gauge may be determined and/or verified utilizing physical measurement. For instance, when a service technician goes to the customer to install DSL service, the service technician checks for the actual values at the serving terminal and reports those values back to imputing system  42  for comparison. Alternately, the telephone company can perform an Adept Test or a MLT to determine the actual values for the distribution record after imputing system  42  has already determined that the customer qualifies for DSL service. Once the actual distribution record values are acquired for the desired cable pair and compared with the imputed distribution record, at step  116  loop engine  62  updates inventory database  52  with the actual values if the imputed values for the desired distribution record differ from the actual values. In addition, once the actual values for the desired distribution record are determined and entered into inventory database  52 , loop engine  62  removes any markings from the desired distribution record indicating that it includes imputed data and the method ends. 
     If at step  104  search engine  60  does not locate the desired cable pair in the known class of serving terminals, then at step  118  search engine  60  searches a sized binder group within inventory database  52  for one or more complete distribution records. As described above, the cable and cable pairs are laid out in telephone network  10  and loops  11  and  13  in binder group pairs where cable pairs in the same binder group are likely to have similar values in the distribution records. The size of the binder group searched by search engine  60  at step  118  depends on how many times search engine  60  has searched binder groups within inventory database  52  for the desired distribution record. When search engine  60  has not searched any binder groups within inventory database  52 , then search engine  60  begins by searching a 10-pair binder group. For instance, the desired cable pair is cable pair number  102  that terminates at serving terminal  20 . When search engine  60  first searches a sized binder group, here a 10-pair binder group, search engine  60  searches cable pair numbers  101  through  110  for one or more complete distribution records corresponding to cable pair numbers  101  through  110 . Such searching of binder groups is based on the outside plant construction principles that cable pairs in the same binder groups generally exhibit similar values for distance and gauge. 
     If at step  120  search engine  60  locates one complete distribution record within the sized binder group searched within inventory database  52 , then at step  106  loop engine  62  imputes the data from the complete distribution into the desired distribution record. For instance, if the desired cable pair is cable pair number  32  terminating at serving terminal  26 , a search of the 10-pair binder group of cable pair numbers  31  through  40  returns one complete distribution record corresponding to cable pair number  36  having a distance of 1.53 kft and a gauge of 12. Therefore, loop engine  62  imputes 1.53 kft and AWG 12 as the values for the distribution record for cable pair number  32 . Once loop engine  60  imputes the values from the complete distribution record to the desired distribution record, step  108  through step  116  are repeated as described above and the method ends. 
     If at step  120  the search of the sized binder group returns more than one complete distribution record, then at step  122  loop engine  62  determines the imputed value for the desired distribution record based on the analysis of the located complete distribution records. Loop engine  62  may utilize statistical analysis in order to determine the imputed values for the desired distribution record when more than one complete distribution record is located within the sized binder group. For example, a search of a 10-pair binder group may return four complete distribution records. In order to determine the values to impute to the desired distribution record using the four complete distribution records, loop engine  62  may take a pure average value for length and gauge to impute to the desired distribution record, take the median of the four complete distribution records as the imputed value, the 75 th  percentile as the imputed value, the 90 th  percentile as the imputed value, or any other appropriate statistical analysis to determine a value for the desired distribution record when there are one or more complete distribution records in the sized binder group. Once loop engine  62  has determined the values to impute into the desired distribution record utilizing the complete distribution records, at step  124  loop engine  62  imputes those values into the desired distribution record. The process then continues to step  108  where step  108  through step  116  are repeated as described above and the method ends. 
     If at step  120  search engine  60  locates no complete distribution records within the sized binder group, then at step  126  search engine  60  determines if the binder group can be increased and therefore searched again. If the binder group size is not exhausted and can be increased, then at step  128  search engine  60  increases the size of the binder group size searched and then searches the increased binder group size within inventory database  52  at step  118 . For instance, if search engine  60  searched a 10-pair binder group at step  118  and did not locate any complete distribution records, then at step  128  search engine  60  may increase the size of the binder group to a 25-pair binder group and search the 25-pair binder group at step  118  for any complete distribution records. For example, if cable pair numbers  51  through  60  were searched where the desired cable pair number is cable pair number  63  and no complete distribution records were located, then search engine  60  increases the binder group size to a 25-pair binder group and searches cable pair numbers  50  through  75  for one or more complete distribution records. 
     Steps  118 ,  120 ,  126 , and  128  are repeated with an increasing binder group size being searched until either search engine  60  locates one or more complete distribution records at step  120  or until the binder group size is exhausted at step  126 . If no complete distribution records are located in the 25-pair binder group, the binder group increases to a 50-pair binder group, then to a 75-pair binder, a 100-pair binder group, and so forth in 25-pair increments until either a complete distribution record is located or the binder group size is exhausted. If the binder group size is exhausted at step  126  without search engine  60  locating one complete distribution record, then at step  130  loop engine  62  imputes into the desired distribution record a default value and step  108  through step  116  are repeated as described above. The default value may be the longest designed loop and smallest gauge value in the known class of serving terminals and cable pairs. 
     In alternate embodiments, the binder group size that search engine  60  initially searches at step  118  can be of any size and does not have to be a 10-pair binder group. For instance, search engine  60  may first start searching a 25-pair binder group. And the increase in the size of the binder group searched when search engine  60  locates no complete distribution records can be any interval desired by the operator of imputing system  42  such as 5-pair 10-pair, 20-pair, 25-pair, 50-pair, 100-pair, or any other appropriate binder group size interval. 
     The method described in  FIG. 3  allows for the estimation of distribution record values of distance and gauge given the layout of telephone network  10 . An alternate serving terminal or the smallest binder group to which the desired cable pair belongs allows for the best estimation for cable pairs having incomplete distribution records. This eliminates the bias towards higher loop lengths except for the instances where one complete distribution record cannot be located before the binder group is exhausted. 
     Although the present invention has been described in detail with respect to DSL and the LFACS database, it should be understood that the data imputing system and method exploiting the statistical properties of data can be utilized with any database that contains data that can be organized in a hierarchical fashion allowing for the improvement in the completeness and accuracy of the data. Furthermore, the imputing method can be applied to any database wherein a set of rules allows for an inference of relationships between known and missing data in the same dataset. For instance, this methodology can be utilized to improve the completeness and accuracy of other databases such as LEIS, LEAD, PREMIS, and TIRKS. 
     In addition, one of ordinary skill will appreciate that alternative embodiments can be deployed with many variations in the number and type of devices in the system, the communication protocols, the system topology, the distribution of various software and data components among the hardware systems in the network, and myriad other details without departing from the present invention. 
     It should also be noted that the hardware and software components depicted in the example embodiment represent functional elements that are reasonably self-contained so that each can be designed, constructed, or updated substantially independently of the others. In alternative embodiments, however, it should be understood that the components may be implemented as hardware, software, or combinations of hardware and software for providing the functionality described and illustrated herein. In alternative embodiments, systems incorporating the invention may include personal computers, mini computers, mainframe computers, distributed computing systems, and other suitable devices. 
     Alternative embodiments of the invention also include computer-usable media encoding logic such as computer instructions for performing the operations of the invention. Such computer-usable media may include, without limitation, storage media such as floppy disks, hard disks, CD-ROMs, DVD-ROMs, read-only memory, and random access memory; as well as communications media such as wires, optical fibers, microwaves, radio waves, and other electromagnetic or optical carriers. 
     Although the present invention has been described in detail, it should be understood that various changes, substitutions and alterations can be made hereto without departing from the spirit and scope of the invention as defined by the appended claims.