USING DIGITAL GEOSPATIAL INFORMATION TO 

LOCATE SAMPLE UNITS IN THE FIELD

Sarah M. Nusser 

Iowa State University 

Jean Fox 

Bureau of Labor Statistics 

Abstract 

Digital geospatial information is now widely available via the Internet, commercial software, and computer-assisted 

tools. Examples include electronic map and route services, digital photographs, and coordinates obtained from 

global positioning system (GPS) receivers. Digital geospatial data could be used to increase the efficiency of field 

staff operations by providing spatial resources in a mobile computer-assisted environment. However, little is known 

about the effectiveness of alternative formats and how best to present this information to assist field representatives. 

In this paper, we focus on methods for using digital geospatial information to find sample units. Locating 

establishments and housing units in the field can be challenging, especially in recently developed neighborhoods, 

when maps are out-of-date or poorly labeled, or when address information for the sample or reporting unit is 

inaccurate or incomplete. Field representatives often require additional resources to identify difficult-to-locate units 

in the field. We will describe preliminary research and a field study design to investigate the effectiveness of digital 

geospatial materials for locating sample units in the field. The specific goals of the research are to explore the uses 

and challenges associated with different kinds of digital geospatial data for locating a sample unit and to understand 

how screen size impacts one’s ability to use these resources in a mobile field environment. 

1. Introduction 

Sample surveys rely on geospatial information to support nearly all components of the survey 

process. Field representatives, survey methodologists, and researchers use maps and 

photographs for sample selection, interview workload planning, navigation, listing activities, 

updates of map information, data collection, and analyses. 

Geospatial information such as maps, photographs, and other spatial resources are commonly 

used in paper form during the survey process. The increasing availability of these resources in 

digital form is motivating survey methodologists to explore the role of geospatial data in 

computer-assisted data collection activities. However, little is known about how best to use this 

type of information in digital form. For example, questions arise about which materials are best 

for a specific task, how data collectors should use geospatial information in performing a task, 

and how user attributes such as spatial abilities affect which information is most appropriate for a 

particular data collector. 

Psychologists have long studied spatial cognition in humans (Mark et al. 1999). In some 

investigations, the focus is on expressing and understanding spatial concepts in abstract 

situations such as a conversation. Other research focuses on specific tasks requiring spatial 

information. For example, Taylor and Tversky (1992) explore the role of text and map-based 

information in navigation and in ability to recall routes. They specifically consider the 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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effectiveness of route (egocentric perspective) and survey (bird’s eye perspective) information in 

accomplishing these tasks. The work of Taylor and Tversky (1992) is an example of an 

emerging research area that focuses on geospatial information theory and cognitive processes in 

relation to the use of geospatial information. Research to-date primarily focuses on 

commonplace usages of geospatial information, such as navigation within a zoo or on 

automobile trips, and much of the research is performed in a laboratory setting. Real world field 

situations have been explored to some extent, but not within the sample survey context where 

there is a need to develop protocols that meet levels of standardization required to provide data 

of consistent meaning and quality. 

The broad objective of our research is to explore which forms of geospatial information and 

interfaces are most effective in aiding users to accurately locate discrete and identifiable sample 

or reporting units (e.g., housing units, establishments, or sample points on the land). The task of 

finding a location can be parsed into three phases: 

1. orientation, where materials are reviewed in relation to the field representative’s 

position and the target location, and a route to the target location (i.e., the 

establishment) is planned; 

2. navigation, which involves traveling to the vicinity of the location (i.e., to the 

corresponding block, within view of the establishment); and 

3. identification of the specific location of the target unit (i.e., the establishment). 

Each of these three phases call for a slightly different set of digital geospatial materials. For 

example, resources that provide a relatively broad overview are needed during the orientation 

phase to identify one’s own location and the target location on the materials and to plan a route. 

A closer view of a map may be needed for actual navigation during the second phase. For the 

third phase, most of the information is derived from the data provided on the establishment rather 

than on photographic images or maps. 

In this paper, we describe preliminary investigations and the design of a field study to explore 

the use of geospatial data in the field to locate sample units. We begin by presenting information 

on the current use of geospatial materials by Bureau of Labor Statistics (BLS) field staff, as well 

as their ideas on the types of materials and features that would enhance their effectiveness if 

offered in a mobile computing environment. Next we describe a field study being implemented 

to explore the use of global positioning system (GPS) receivers and commercial map software on 

tablet and handheld computing platforms. In the proposed study, we focus on the task of 

locating an establishment in the field for the first time. Early results from this study will be 

presented in our talk, but are unavailable in time for publication. 

2. Current Field Use of Geospatial Resources 

To increase our understanding of how field staff are using geospatial information, BLS regional 

field managers were asked to distribute a set of questions to field staff on their experiences with 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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using spatial information. Staff were asked what types of map-based resources they use, what 

information they obtain from map-based resources to help locate establishments or housing units, 

when map-based resources are most useful, and what problems are encountered when using mapbased resources. After reviewing these responses, a teleconference was held with field staff from 

regional offices to discuss the results of this survey and to obtain more detailed information on 

field use of geospatial information for locating establishments. 

Written and oral responses indicated that maps of widely varying forms are heavily used by field 

staff and their managers. This points to the importance of this resource in the day-to-day 

operations of the field staff. The lack of homogeneity in map-based resources primarily results 

from the need to augment map resources beyond those provided by national staff. 

In large urban centers, field staff commonly use map books that contain gridded maps and 

multiple reference indices available for identifying a location. Commercial organizations 

producing the best map products (e.g., ADC, Thompson) vary across regions; a single vendor is 

not available to provide quality maps for the entire U.S. Web-based products for these

companies are very limited relative to the paper map products. 

Several staff members also use Internet map resources (e.g., MapQuest) and/or map-based 

software products produced by Microsoft. This year’s version is called Streets & Trips 2001 

(http://www.microsoft.com/streets), and comes with a PocketPC / WinCE package for 

downloading map products to a handheld device running a MS operating system. Field staff 

noted that Internet maps are not always accurate, and that little is known about how digital map 

sources are updated by private vendors. No one discussed the use of GPS receivers in their 

work, although a few staff members had driven cars with GPS-based navigation systems. 

To plan field work and to navigate to locations, field representatives rely heavily on spatial 

resources. Coarse-scale views allow one to consider multiple addresses; focused views to 

identify locations and determine routes for traveling from point to point. Although map 

resources often provide information on distance for a route, time is also an important metric for 

the survey setting. Map software features that may help support navigation include route 

planning utilities that can be updated when plans change, digital maps with a clear indication of 

one-way streets, and an interface that can be easily interpreted while driving. 

In discussing computer-based tools for navigation and field planning tools, field staff commented 

on several features that may be useful. For example, it may be possible to use audio instructions 

to provide a safer interface when driving. However, this has the limitation of only providing 

route-based (rather than overview) information, making it difficult to find a new route when 

unexpected situations arise (e.g., construction, one way street) unless the ability to adjust the 

route has been built into the software. Important landmarks that assist navigation to and 

identification of a location include schools, churches, cemeteries, shopping centers, airports, and 

parks. Field representatives noted that labels and icons with varied coloring were needed to 

distinguish and identify landmarks. The ability to display a map at different scales enables a 

representative to use the digital maps for different tasks (planning for multiple addresses vs. 

identifying the location of or a route to a single address). Finally, some packages allow the field 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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user to draw on or annotate an image, and this was also viewed as an important tool for locating 

and for future uses of the map during revisits. 

Field staff use multiple kinds of information to identify addresses and outlets, in part due to 

variability in the completeness and quality of information provided to the field staff. Further, the 

types of problems encountered in location information vary across community settings, with the 

age of the development, and with the difficulty of locating businesses. Map resources may 

contain inaccuracies due to errors or lack of timely information. Streets for a geographic region 

may be missing or incomplete (e.g., recent construction), or individual or sets of features may be 

misrepresented. 

The net result is that field staff must “triangulate” among information resources (e.g., map, BLSprovided address, yellow pages, internet) to develop an understanding of the likely ground 

situation. Boundaries for zip codes and other divisions are useful in helping to resolve

inconsistencies in information. One type of information that has not been used by field staff is 

aerial photography. Many thought that aerial photographs may be too complex for field staff to 

interpret, unless landmarks (or thermal imaging) could be combined with the photograph to 

provide the field representative with reference information. 

Ideally, digital spatial resources are loaded on to the computer that the field representative uses 

for data gathering. Field staff indicated that a palm-size computer would be acceptable for a 

second computer, but that larger computers would not. Concerns were expressed about the

robustness of the smaller computers in extreme environments. 

One potential concern is the skill level needed to work with digital geospatial information. 

However, because of the importance of maps in field work under the current setting, staff must 

have adequate map skills to successfully complete their work regardless of whether resources are 

paper-based or electronic. Thus the population of field representatives does not contain persons 

who are largely unable to interpret maps, although training may be needed to become effective in 

locating outlets. Basic training in map reading skills is provided to assist in planning and 

executing location and navigation tasks. This training is tailored by the data collector’s 

supervisor to reflect needs of the specific job. For example, staff are given an introduction to 

different types of maps, how to set up and interpret a map, how to use a map for a specific task, 

how to use cross-indices (features, grids, etc.), and strategies for different types of location 

situations. Areas that field staff have the most trouble with include identifying the cardinal 

directions (e.g., finding north or the northwest corner) and finding one’s current location on the 

map. 

Field staff noted several areas in which they could benefit from better geospatial data. These 

include: 

•฀ To identify the location of sample units for which inaccurate information was provided, 

•฀ To support staff members who are unfamiliar with an area because they have been 

imported from other regions or locations due staffing problems, 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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•฀ For the address refinement process that yields the address information provided to field 

staff conducting initiation (finding and contacting an establishment or household for the 

first time), 

•฀ For the initiation process when poor address information is provided to the field staff, and 

•฀ For updating routes and strategies when conditions in the field have changed 

unexpectedly. 

Based on this preliminary investigation, we developed a small study to examine the effects of 

commercial map products and GPS information on the ability of field staff to locate 

establishments. The specific setting for this study is described in Section 3 and the study design 

is outlined in Section 4. 

3. Study Setting 

The target task for this study is locating an establishment in an urban setting as part of the 

initiation phase of the Commodity and Services Survey (C&S), conducted by BLS to obtain 

pricing information for the Consumer Price Index (CPI). We focus in particular on more 

difficult cases of locating establishments. For example, professional service offices (e.g., 

lawyers, dentists, accountants) may have signage that is not as recognizable as a franchise 

establishment, or they may be housed within a poorly marked building with other professional 

service units. These more challenging settings are likely to benefit the most from having 

accessible digital geospatial information resources. 

During the initiation phase of C&S, field representatives must follow established procedures to 

find an establishment, but they have some freedom to determine exactly how to carry out the 

procedures. Prior to going out into the field, a field representative typically does some 

background work to help locate the establishment. S/he may review yellow and white page 

directories, street maps, and perhaps make a phone call to the establishment to obtain directions. 

However, office preparation of this type is not always feasible. Indeed, it may be more efficient 

to have access to digital resources on the road in case plans need to be altered during the day. 

The field study will involve providing BLS field staff with alternative supporting resources for 

the task of finding establishments (also called outlets) during the C&S initiation process. 

4. Proposed Field Study 

4.1 Objectives

The overall objective of the proposed research project is to explore the potential benefits and 

challenges of using digital geospatial information, in the form of electronic maps and locations 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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obtained from GPS receivers, to locate outlets in a mobile computing environment. The specific 

goals of the research are: 

•฀ To explore the potential uses and problems associated with commercial-off-the-shelf 

(COTS) map products for specific tasks associated with locating a sample unit (e.g., 

planning, navigating, finding unit), 

•฀ To study the benefits and usability issues associated with integrating GPS information 

with COTS map products, 

•฀ To investigate the impact of the screen size of a mobile computer on the use of these 

resources (both the ability to use them and how they are used), 

•฀ To improve our understanding of strategies and tools employed by field staff to make 

best use of multiple spatial resources in finding outlets, and 

•฀ To obtain information on the learning process for using these tools to further understand 

the training issues associated with these technologies. 

Addressing these objectives is a crucial step in developing a foundation for the emerging age in 

which current and accurate geospatial data are increasingly available and in which on-the-fly 

integration of different forms of spatial data is possible. 

4.2 Experimental Factors 

We propose to investigate two factors in our study: the size of computer (and thus visual 

interface) used by the field representative, and the type of geospatial information made available 

to the field representative. 

The first factor to be studied is the type of device, in particular, the size of interface. Personal 

digital assistants are common palm-sized devices that are extremely portable. The high quality 

color interfaces now available provide a viable interface for presenting complex visual 

information such as spatial data. Although map software provides zoom capabilities that enable 

the field representative to select an image scale that best fits her/his needs for a particular phase 

of the locating process, a palm-sized device may not provide an adequate interface, for example, 

to provide overviews during the orientation phase. A tablet computing environment provides a 

potential compromise between screen real estate needs and mobility, although it still presents 

ergonomic difficulties. To explore this issue, we will use two types of devices in our study. One 

will be a lightweight palm-sized computer (Compaq iPaq, Figure 1a, 2 1⁄4 x 3” viewable screen 

area, Pocket PC operating system) and the other will be a tablet computer with a larger interface, 

but heavier form (Fujitsu 3400, Figure 1b, 10.4” diagonal screen size, Windows 98 operating 

system). 

For the second factor, two types of digital geospatial resources will be studied. First, software 

that creates digital maps annotated with street names and other features will be made available to 

the field representative. We have selected Microsoft’s Streets and Trips because it provides 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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these features and is already used by a small number of field staff on their home computers. One 

problem with a map is that it can fail to provide the kind of perspective or features needed to 

understand one’s current location. An alternative option is to use a GPS receiver to indicate the 

field representative’s location on the digital map. Thus, the second type of spatial resource will 

be a GPS receiver that indicates the field representative’s location on the digital map. Examples 

of the two levels proposed for the geospatial resource factor are presented in Figure 2. 

The Streets and Trips software can be run on both Pocket PC and Windows 98 devices, so the 

interface will be roughly uniform across computing platforms. However, the PocketPC version 

does not support GPS, so the GPS treatment will only be applied on the tablet level of the device 

factor. Thus the treatment conditions will be as follows: 

•฀ Handheld with map software, 

•฀ Tablet with map software, and 

•฀ Tablet with map software and current position from GPS receiver displayed on map. 

Each field representative that participates in the study will be given several outlets for each 

treatment. The treatments will be ordered to reduce the difficulty of introducing experimental 

materials to the field representative. 

The usual initiation procedures employed by field staff will also be observed as a benchmark or 

control condition. This will be done prior to administering the experimental conditions so that a 

clean assessment may be made. 

4.3 Identifying sample outlets 

The August 2001 C&S sample was reviewed in order to identify primary sampling units that 

have a sufficient density of hard-to-find outlets. The “type of business” code was used to 

identify such establishments. For the PSUs selected, business types include legal services, lawn 

and garden services, housekeeping, furniture reupholstery, and home-based repair services. 

Our goal is to gather information from two to four primary sampling units, pending the 

availability of experimental resources. The number of outlets per control or treatment condition 

will depend on the number of hard-to-find outlets available in the PSU. 

4.4 Field operations 

Prior to training, the field representative will be given a short questionnaire to complete. The 

preliminary questionnaire includes diagnostic question sets for spatial strategies and abilities; 

prior experience with computers, GPS, establishment initialization, and the layout of the 

initialization area; and demographic information such as age and gender. 

The field representative will then initiate four to eight control outlets using their usual procedures 

and asked to record observations on this process. Following the control outlets, the field 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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representative will be trained to use the map software on the tablet (field staff have used the 

tablets in the past), and will be given three or four new outlets to locate using the tablet and the 

map software. Field staff will then be trained on use of the handheld device, which has the same 

map software, and asked to initiate an additional set of outlets. Finally, the field representative 

will be shown how the GPS link works on the map software on the tablet platform, and an 

additional set of outlets will be done. The field representative will be given a questionnaire after 

each treatment session to record information on their experiences with the treatment setting. 

Questions include which features were used, for which components of the locating task were 

materials used, how effective the resources were, what types of problems arose, and additional 

features or resources that would have been helpful. The investigators plan to observe all aspects 

of the use of these materials. 

In order to allow the field staff to become familiar with the equipment and software, the 

materials will be left with the field representative for initiating additional outlets over the 

subsequent one or two months. A final field visit will be made by the investigators to assess the 

efficacy of these materials when the field representative is more familiar with them. 

Results from the initial field visit will be reported on during the conference. 

Acknowledgements 

The authors wish to acknowledge support provided by the Bureau of Labor Statistics, the 

ASA/NSF/BLS Research Fellowship Program, and the NSF Digital Government program in 

conducting this research. 

References 

Mark, D. M., C. Freska, S. C. Hirtle, R. Lloyd and B. Tversky. 1999. Cognitive models of 

geographical space. International Journal of Geographical Information Science, 13:747−774. 

Taylor, H. A. and B. Tversky. 1992. Spatial mental models derived from survey and route 

descriptions. Journal of Memory and Language, 31:261−292. 
 

 

 

 

 

 

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(a) (b) 

Figure 1. Devices with different interface dimensions to be used in the field study: (a) Compaq iPAQ and (b) 

Fujitsu 3400 tablet. 

(a) (b) 

Figure 2. MS Streets and Trip 2001 map (a) without GPS link and (b) with GPS link denoted by dark circle.