United States 

 Department of 

 Agriculture

 

 

 National

 Agricultural 

 Statistics 

 Service

 Research and 

 Development Division

 Washington DC 20250

 RDD Research Report 

 Number RDD-05-04

 October 2005 

Using Handheld Global 

Positioning System 

Receivers for Phase II 

of the Agricultural 

Resource Management 

Survey 

Michael W. Gerling 

This paper was prepared for limited distribution to the research community outside the United States 

Department of Agriculture. The views expressed herein are not necessarily those of the National 

Agricultural Statistics Service or of the United States Department of Agriculture. 

i 

EXECUTIVE SUMMARY 

In July 2004 the Washington Field Office (WA FO) asked the Research and Development 

Division to study the practicality of using handheld Global Positioning System (GPS) receivers 

for the Agricultural Resource Management Survey Phase II (ARMS II). Specifically the WA FO 

wanted their field enumerators to use the receivers to obtain latitude and longitude coordinates of 

the sampled fields in place of using county highway maps and the DLG Map software. The 

expectation was that equipping enumerators with low-cost GPS receivers would save the FO 

valuable staff time by eliminating the use of the labor-intensive DLG Map software. 

Hence, a research project was born. Each WA FO field enumerator working on the survey was 

supplied with a Garmin GPS-72 receiver. Overall, the field enumerators had no problem using 

their GPS receivers to obtain the latitude and longitude coordinates of the sampled fields. 

Ideally, the goal is to obtain the center point of the field; however, the enumerators were 

instructed to obtain a reading at the edge of the field for practicality purposes. 

Of the 211 completed reports, twenty-two operations had fields that could not be accessed by the 

field enumerator. The two main reasons for this were that the operator refused permission for 

the field enumerator to visit his/her field or the weather conditions made the fields inaccessible. 

Highlights of the research project’s cost/benefit analysis are provided below: 

Costs Benefits 

$5,100 Equipment & supplies. 

$1,600 Additional field enumeration costs. 

3 hrs. FO statistician time. 

Obtaining lat/long coordinates for ARMS II 

isn’t always an annual requirement for some 

FOs. Thus, GPS receivers may not be an 

annual benefit for these FOs. 

One GPS receiver failed to be returned. 

19.1 hrs. Overall statistician time saved. 

 Apply time to other projects. 

Data quality improved. 

Re-use the GPS receivers over multiple years 

for ARMS II and/or other projects. 

Lat/Long coordinates completed 60 days 

earlier. No longer a post survey activity. 

Reduces the need for DLG Map software. 

ii 

RECOMMENDATION 

1. Recommend implementing the use of GPS receivers for the Agricultural Resource 

Management Survey Phase II. Also, recommend continuing the use of county highway 

maps for those cases when the fields are inaccessible or the GPS receivers fail. 

1 

 

Using Handheld Global Positioning System Receivers for Phase II 

of the Agricultural Resource Management Survey 

Michael W. Gerling1

Abstract 

The National Agricultural Statistics Service conducts hundreds of surveys on 

United States and Puerto Rico agriculture for the purpose of making estimates on 

crops, livestock, production practices, economics, etc. One of these surveys

conducted annually is the Agricultural Resource Management Survey. The 

survey has multiple purposes ranging from collecting information on chemical use 

and production practices on specific targeted crops to obtaining information on 

the financial well-being of agricultural operations. 

One aspect of the survey requires obtaining the latitude and longitude coordinates 

of sampled agricultural fields containing the target commodity. The current 

method involves the enumerator marking the location of these fields onto county 

highway maps, followed by the use of mapping software by office staff. This

process is time consuming and lends itself to human error. 

Hence, the Research and Development Division and the Washington Field Office 

joined efforts to investigate whether equipping field enumerators with low-cost 

handheld GPS receivers would save staff time and improve the accuracy of 

recording where the sampled fields are located. 

KEY WORDS: Agricultural Surveys, Data Collection, GPS

1 Michael W. Gerling is a Mathematical Statistician with the National Agricultural Statistics 

 Service - Research & Development Division, located at Room 305, 3251 Old Lee Highway, 

 Fairfax, VA 22030. A special thanks to the Washington Field Office, Washington’s 

 Field Enumerators, Matthew Pautler, Stacy Wills, Dan Beckler, and Matthew Fetter for their 

 dedication and commitment in making this research project a success. 
2 

1. INTRODUCTION

The National Agricultural Statistics 

Service’s (NASS) mission is to provide 

timely, accurate and useful statistics on 

United States and Puerto Rico agriculture. 

NASS conducts hundreds of surveys for the 

purpose of making estimates on crops, 

livestock, production practices, economics, 

etc. 

The Agricultural Resource 

Management Survey (ARMS) is a multipurpose national survey conducted each year 

for varying commodities. ARMS is the 

primary vehicle by which NASS obtains 

data on chemical use and production 

practices for target commodities. ARMS 

also collects economic information used to 

assess the financial well-being of the 

agricultural sector. 

To optimize data collection efforts, 

NASS investigated using Global Positioning 

System receivers to obtain the latitude and 

longitude coordinates of the sampled 

agricultural fields containing the target 

commodity.

2. ARMS

The Agricultural Resource 

Management Survey provides information 

about agriculture’s economic status and its 

impact on the quality of the environment. 

The ARMS is the primary source of 

economic data providing a true picture of 

the financial well being of all U.S. farms. 

The ARMS is composed of three 

phases. Phase I, conducted May through 

July, is the screening phase which 

determines whether the operation is in 

business, its type of operating arrangement, 

and whether the operation has those 

commodities targeted for the survey. 

Phase II, conducted October through 

December, focuses on chemical use and 

production practices on target commodities. 

The targeted commodities for 2004 were 

soybeans, peanuts, winter wheat, durum 

wheat and all other spring wheat. 

Phase III, conducted February 

through April of the following year, pertains 

to the financial condition of the farm sector, 

including income, expenses, assets, and 

debt. Operator characteristics are also 

collected. 

2.1 PHASE II

Phase II of the 2004 Agricultural 

Resource Management Survey is the focus 

of the research project and this report. 

Operations sampled in Phase II are 

personally interviewed by field enumerators 

using paper questionnaires. For each 

selected operation, a substantial number of 

questions are devoted to collecting data on 

the targeted commodity in the sampled field. 

Historically, a field enumerator 

shows a county highway map to the 

respondent and asks him/her to point out the 

location of the sampled field (in particular 

the center point). The field enumerator then 

marks a red X for the field location and 

writes the operation’s ID beside the X to 

identify it. Of course, this step of 

interpreting the location on the map and 

marking the map lends itself to human 

errors. 

After Phase II data collection is 

complete, the county highway maps are 

returned to the field offices. 

Next, office staff utilize the mapping 

software, DLG Map, to obtain the latitude 

and longitude coordinates of the red Xs 

recorded on the county highway maps. 

DLG Map is a digital street map software 
3 

that displays roads, streams, and lakes. 

Office staff navigate within DLG 

Map and, to the best of their ability, mark 

the location that corresponds to the X on the 

county highway map. Overall this process is 

time consuming and also lends itself to 

human error. 

Next, DLG Map translates these Xs 

into latitude and longitude coordinates and 

creates a text file with the coordinates. This 

file is then sent to NASS’ main data 

processing facility in Kansas City, Missouri. 

Finally, the DLG Map files from all 

states are reviewed by NASS Headquarters 

staff before being sent to the Economic 

Research Service (ERS), another agency of 

the United States Department of Agriculture, 

for further analysis. 

Geo-coding (linking multiple data 

sources together based on physical location) 

of the targeted fields is vital to ERS. These 

data allow ERS to better understand how 

farmers affect, and are affected by, soil 

quality, soil erosion, water quality, urban 

influence and climate. This knowledge is 

critical in making informed policy decisions. 

Specifically, ERS wants to be able to 

identify the exact location of the fields that 

the ARMS data come from so as to match 

these data with those obtained from the 

Farm Service Agency. 

3. BIRTH OF A RESEARCH 

PROJECT 

In July 2004 NASS’ Washington 

Field Office (WA FO) asked NASS’ 

Research and Development Division to 

research the practicality of using handheld 

Global Positioning System (GPS) receivers 

for the Agricultural Resource Management 

Survey - Phase II (ARMS II). The 

expectation was that using low-cost 

handheld GPS receivers to obtain the 

latitude and longitude coordinates would 

improve the quality of the data and enable 

the WA FO to save office time by not 

having to use the labor-intensive DLG Map 

software. 

Hence, the Washington Field Office 

and the Research and Development Division 

agreed to investigate the use of handheld 

GPS receivers for ARMS II in the hope of 

saving office staff time. 

4. WHAT IS A GPS HANDHELD 

RECEIVER?

The Global Positioning System is 

comprised of at least twenty-four satellites 

orbiting the earth. These satellites transmit 

signals to GPS receivers on the ground. The 

majority of GPS receivers are about the size 

of a standard television remote control. 

A GPS receiver only receives signals 

from the satellites. It will not transmit. To 

function properly, a GPS receiver also 

requires an unobstructed view of the sky. 

First, the GPS receiver acquires 

signals from these various satellites. Next, 

the GPS receiver determines the location of 

the satellites from the information included 

in the satellites’ transmissions. The receiver 

then determines the distance it is from each 

satellite. Finally, the receiver is able to 

determine where it is actually located on the 

Earth within a certain level of accuracy. 

The receiver displays its location in 

latitude and longitude coordinates. Latitude 

measures the distance north or south from 

the Equator while longitude measures the 

distance east and west from the Prime 

Meridian. 

A common use of GPS receivers is 

for hiking. Hikers utilize these receivers to 

trace their trail or to mark a unique location 
4 

that they would like to return to at a later

date. 

The particular GPS receiver selected

was the Garmin GPS-72. See Figure 1. 

Figure 1: Garmin GPS-72 

Garmin was selected since the company has

been a respected manufacturer of GPS 

receivers for 15 years. The GPS-72 model

was also among the lowest-price GPS 

receivers offering the Wide Area 

Augmentation System (WAAS). WAAS 

provides the potential to obtain a level of 

accuracy of ten feet. Typically, the GPS-72 

receiver will provide a level of accuracy

between 10 and 50 feet. 

5. THE RESEARCH PROJECT 

All thirty-three Washington FO field 

enumerators working on ARMS II were 

supplied with a Garmin GPS-72 receiver. 

Washington’s 2004 ARMS II sample

size was 300 agricultural operations. Winter 

wheat was the targeted crop. 

For all 300 agricultural operations, 

field enumerators were instructed to go to

the edge of the field and, using their GPS 

receivers, obtain the latitude and longitude

of the sampled field and record these 

coordinates on the paper questionnaire. 

Appendix A contains a copy of the page of 

the questionnaire where the coordinates

were to be recorded. Although the goal is to 

obtain the center point of the field, entering 

the field was not required since fields are 

generally irregular in shape which would 

make determining the center point 

impossible. Also, NASS wanted to 

minimize the amount of intrusion in the 

fields to prevent any crop damage. Finally, 

it was deemed impractical to take multiple

readings around a field’s edge and calculate 

the center point through triangulation. 

The enumerators were also asked to

record any mileage and time it took to 

access the field and obtain the latitude and

longitude coordinates. These additional 

expenses were not incurred during the 

county highway map process since going to 

the sampled field was not needed. A copy 

of the Enumerator-GPS Receiver Usage 

Form is provided in Appendix B. 

For half of the samples (150), field 

enumerators were instructed to additionally

proceed with their regular routine of 

recording where the sampled fields were 

located on the county highway maps. 

Additionally, the Washington FO 

was to record the amount of time and 

number of staff required to use the DLG 
5 

Map software to obtain the latitude and 

longitude coordinates from the marked 

county highway maps. See Appendix C for 

a copy of the DLG Map Time Keeper Form. 

5.1 ENUMERATOR TRAINING 

Each year a survey workshop is 

conducted to train field enumerators on 

ARMS II data collection procedures and 

specifics of the questionnaire. Training 

these field enumerators to use the GPS 

receivers was incorporated into this 

workshop. 

Small group instruction was 

employed for teaching GPS receiver use, 

with each group consisting of a supervisory 

field enumerator and his/her enumerators. 

Hence, there were a total of six groups with 

approximately five enumerators per group. 

 Training consisted of going outside 

and learning how the GPS receivers 

acquired satellites and operated. Each 

enumerator was also supplied with written 

instructions on how to operate the GPS 

receiver. The training lasted about 20 

minutes per group and was incorporated into 

the workshop in such a way that while a 

particular group was learning their GPS 

receivers, the other groups were reviewing 

their survey manual. One statistician was 

responsible for all GPS training preparations 

and instruction which totaled three hours. 

6. RESULTS

Two hundred eleven (70.3%) of the 

300 operations sampled completed their 

ARMS II report. The 89 operations that did 

not have completed reports were due to the 

operator refusing to complete the 

questionnaire, the enumerator being unable 

to locate the operator, the operation being 

out of business, or the operation not having 

the targeted crop. 

Of the 211 completed reports, 

enumerators were unable to obtain 

coordinates for selected fields in only 22 

cases (10.4%). The primary reasons cited 

for this were rainy weather making the fields 

inaccessible and agricultural operators not 

wanting enumerators in or around their 

fields. 

 As far as the capability of the GPS 

receivers was concerned, there was only one 

account of the GPS receiver failing to 

acquire coordinates. The reason for this is 

unknown. However, a problem that a few 

field enumerators encountered was that 

when the GPS receiver’s batteries started 

running out of power a "low battery" 

warning message would appear. This 

warning message overlaid the entire display. 

Thus, the installation of new batteries was 

required in order to continue using the 

receiver. Hence, carrying a spare set of AA 

batteries became a necessity. In general, 

the GPS receivers operated flawlessly. 

 The enumerators also recorded their 

additional time and mileage to reach the 

field to record the latitude/longitude 

coordinates from the GPS receiver. The 

average additional time and mileage for an 

enumerator to obtain latitude/longitude 

coordinates was 20 minutes and 9 miles per 

field. See Figures 2 and 3 located on the 

following page. These statistics include 11 

reports where time and/or mileage were 

incompletely reported. The missing data 

were estimated by using the average time 

and/or miles that the enumerator took for 

completing GPS readings at other operations 

along with any notes supplied on the 

enumerator’s incomplete feedback form. 

This was done to achieve the best data set 

possible. 
6 

Figure 2: 

Enumeration Time in Locating and Obtaining the GPS Coordinates 

for Each Completed Report

77

54

32

4 8 6 8

0

20

40

60

80

100

 0 - 10 >10 - 20 >20 - 30 >30 - 40 >40 - 50 >50 - 60 >60

Enumeration Time (Minutes)

No. of Rep

orts .

Figure 3: 

Enumeration Mileage in Locating the Fields to Obtain GPS

Coordinates for Each Completed Report

40

70

36

12 8 5 5 7 3 3

0

10

20

30

40

50

60

70

80

0 >0 - 5 >5 - 10 >10 - 15 >15 - 20 >20 - 25 >25 - 30 >30 - 40 > 40 - 50 >50

Miles

No. of Rep

orts
7 

 There were three outliers of time and 

mileage recorded by three enumerators for 

different fields. These are shown below: 

150 minutes and 70 miles 

120 minutes and 88 miles 

 120 minutes and 60 miles 

These three outliers were due to the general 

interview being conducted at night and the 

enumerator having to return the next day 

during daylight hours to access the field. 

Interviews in the evening will continue to be 

a fact of life since farmers often work from 

daylight to dark, and they are available for 

interviews only in the evenings. 

An oversight in the design of the 

enumerator feedback form was that it failed

to ask for the additional time and mileage 

incurred in the 22 instances when the 

enumerators tried unsuccessfully to access 

the sampled fields and therefore could not 

obtain a GPS reading. This was brought to 

light when some of the enumerators ignored 

the form’s skip patterns and completed the 

time and mileage anyway.

 Of the 150 sampled fields originally 

selected to be marked using both the county 

highway maps process (as well as the GPS 

receiver process), 98 were ultimately 

marked on county highway maps. An 

experienced statistician in the WA FO was 

assigned to use DLG Map to obtain the 

latitude and longitude coordinates for the Xs 

on the county highway maps. 

 A little background information on 

DLG Map is worth noting. The software is 

an in-house package which was developed 

in 1991 by Martin Ozga of NASS. 

Basically, DLG Map is a road map software 

that displays roads, rivers/lakes, and 

railroads for each state. The user can zoom 

in at the county and street level to locate, to 

the best of his/her ability, the area that 

represents the X on the county highway 

map. 

The statistician, having DLG Map 

experience, spent 11.5 hours using DLG 

Map to obtain the latitude and longitude 

coordinates for the 98 Xs marked on the 

county highway maps. This averages to 

seven minutes per county highway map 

point and was done over a period of three 

days. 

6.1 DLG MAP & GPS RECEIVER 

COMPARISON 

 The method of using GPS receivers 

versus the county highway map & DLG 

Map process was compared. 

Of the 98 sampled fields marked on 

county highway maps, 93 also had GPS 

readings obtained. The difference of five 

fields was due to inaccessible fields or fields 

that the operators did not want the 

enumerators around. Hence, a total of 93 

sampled fields had latitude and longitude 

coordinates obtained by both methods. 

 First, the differences between the 

measurements of latitude and longitude of 

both methods were examined. All 

measurements are in degrees. 

 A standard univariate paired t-test 

was performed on the observed differences 

for latitude and longitude recorded by the 

two methods, as well as a univariate 

student’s t-test and ranked sign test of 

Ho(Null hypothesis): no difference in 

latitude or longitude measurements versus 

Ha(Research hypothesis): a positive absolute 

difference in the measurements. These tests 

were unable to detect any significant 

difference at the alpha level of 0.10 for 

either latitude or longitude. Simply stated, 

these tests didn’t show any evidence of a 

statistical difference between the two 
8 

methods. The inability of the tests to show 

any difference (even with removing the top 

four outliers) is probably due to the 

observed differences having very small 

means and relatively large variances, with 

coefficients of variation over 900 percent for 

longitude and latitude. See Table 1. The 

tests were conducted in degrees so that there 

would be the opportunity for positive and 

negative differences. Using miles would 

only have provided positive values since 

distance can not be negative. This would 

have caused the tests’ results to be 

meaningless. Figures 4 and 5, located on the 

following page, show the dispersion of the 

differences in latitude and longitude 

between the two methods per field. 

 

Table 1: Differences in Latitude and Longitude Between the GPS and DLG 

Map Methods. (Measured in Degrees. Excludes top four outliers.) 

Differences in Latitude Between 

GPS and DLG Map Methods 

Differences in Longitude Between 

GPS and DLG Map Methods 

Mean -0.001941 Mean 0.006604 

Standard Error 0.018161 Standard Error 0.061770 

Coefficient Variation -935.48% Coefficient Variation 935.31% 

Test Statistic P Value Test Statistic P Value 

Student’s t -1.0085 0.3160 Student’s t 1.0086 0.3159 

Signed 

Rank 

-236.5 0.3112 Signed 

Rank 

105 0.6482 
9 

Figure 4: 

Scatter Plot (X,Y): where X= Latitude (GPS - DLG Map) and

Y = Longitude (GPS - DLG Map) per Field.

-0.6

-0.4

-0.2

0

0.2

0.4

-0.5 0 0.5 1 1.5 2 2.5 3

Difference in Longitude (Degrees)

Difference i

n Latitu

d

e (

Degrees)

Figure 5:

Zoomed-InView of Figure 4: Scatter Plot (X,Y): where X= Latitude

(GPS - DLGMap) and Y = Longitude (GPS - DLG Map) per Field.

-0.01

-0.005

0

0.005

0.01

-0.01 -0.005 0 0.005 0.01

Difference in Longitude (Degrees)

Difference i

n Latitude (Degrees)
10 

Next, the physical distance between 

the two methods’ coordinates in miles were 

examined using a different approach. In 

Washington, degrees of latitude and 

longitude translate to the following: One

degree of latitude is approximately 69 miles

and one degree of longitude is 

approximately 47 miles. 

The Greater Circle Distance Formula 

was used to calculate the distance between

the coordinates of the two methods. The

formula, shown below, measures the number 

of miles between two points if the 

coordinates of those points are in decimal 

degrees. 

[3963.0 · arccos(sin(latitude of GPS ÷

57.2958) · sin(latitude of DLG Map ÷

57.2958) + cos(latitude of GPS 57.2958) · 

cos(latitude of DLG Map 57.2958) · 

cos((longitude of DLG Map 57.2958) – 

(longitude of GPS 57.2958)))] where the 

radius of the Earth is stated at 3,963.0 miles. 

÷

÷

÷

÷

This formula accounts for the curvature of 

the Earth instead of just calculating a

straight line distance. Of the 93 comparable 

points, there was one dramatic outlier whose 

GPS receiver reading was 132 miles 

different from those provided by DLG Map. 

The average distance was 1.9 miles and the 

standard error was 4.2 miles, excluding the 

outlier. Twenty-nine points or 31 percent 

had over a mile difference between the two 

methods. Even if the level of accuracy of 

the GPS receivers were a dismal 50 feet=

0.01 miles, the amount of inaccuracy of the

GPS receivers does not account for the 

difference between the two methods. See 

Figure 6 for a frequency distribution of the 

distance between the GPS Method and the 

DLG Map method. 

Finally, the winter wheat fields’ sizes 

were examined. The average land area of 

the fields was 0.27 square miles. Hence, 

unless there was an unusually long skinny 

field, the same 31 percent of the coordinates, 

noted above, obtained by DLG Map would 

have no probability of falling inside the field 

that they are trying to represent. This 

percentage may actually be substantially 

greater but was unable to be statistically

justified. 

Hence, the use of GPS receivers 

would improve the quality of the coordinates 

provided to ERS. This improved data 

quality would help ERS determine the actual 

field and thus improve their ability to 

accurately overlap other data with NASS 

ARMS II data. 

The estimated time saved in the field 

office by having the enumerators use GPS 

receivers is 19.1 hours. This was calculated 

by first taking the average amount of time it 

took to plot a point using DLG Map 

multiplied by the total number of completed

reports, (7 minutes per point · 211 reports = 

24.6 hours). However, 22 of the 211 

completed reports did not have GPS 

readings and still would have needed to be 

DLG Mapped which is estimated at 2.5 

hours, (22 · 7 minutes per point). Also, the 

statistician spent a total of three hours in 

preparing training materials and in training 

the field enumerators. Hence, the total staff 

time saved is 24.6 hours minus 2.5 DLG 

Map hours and minus the 3.0 hours of 

training which equates to 19.1 hours of total 

time saved in the field office. 
11 

Figure 6: 

Distance Between the

GPS Method and the DLG Map Method

48

16

10 13

6

0

10

20

30

40

50

60

0 - 0.5 >0.5 - 1 >1 - 2 >2 - 10 >10

Miles

No. of Fields

6.2 COST - BENEFIT ANALYSIS 

Conducting a cost-benefit analysis 

on the research project allows NASS to 

determine whether expanding the use of 

GPS receivers to more FOs for ARMS II 

should be implemented or not. 

The total operational expenditures 

for the research project were $6,700 and 

three hours of a WA FO statistician’s time. 

The cost breakdown follows. 

Thirty-five Garmin GPS-72 receivers

were purchased for a total cost of $4,961. 

This provided each ARMS II enumerator 

with a GPS receiver and allowed for two

spares. One spare receiver was held by the 

WA FO and the other by the Research and

Development Division for additional 

studying. 

Miscellaneous expenditures are 

estimated at $100. This includes the 

purchase of spare AA batteries (2 extra 

batteries per enumerator), paper to print the 

GPS instructions on, etc. 

The cost incurred by the additional 

enumerator time in reaching the field and

using the receivers (including salary and 

benefits) was $4.13 per sample field. This 

calculates out to a total of $780 in 

enumerator salary and benefits. 
12 

 The additional mileage incurred in 

reaching the sampled fields equated to $3.24 

per field. At the time of enumeration, 

NASS’ reimbursable mileage rate was 37.5 

cents a mile. This expands to a total 

additional mileage cost of $613. 

 The GPS training of the thirty-three 

enumerators (20 minutes per enumerator) 

was expensed at $130 (includes salary and 

benefits). 

 Costs of the hotel and conference 

room were excluded since the GPS training 

was incorporated into the regularly held 

ARMS II workshop. 

Enumerator costs for the 22 

instances where a GPS reading could not be 

obtained was estimated at $89. This was 

calculated using the following method. 

Eleven feedback forms contained a reason 

why the enumerator was unable to obtain a 

GPS reading. Four times, equivalent to 36 

percent, the operator refused access to 

his/her fields. Seven times, 64 percent, the 

enumerator could not physically get to the 

field. Of these seven times, three had 

mileage and time costs. These costs were 

then expanded to cover the 4 reports that 

didn’t have costs reported. This left 11 

cases, 50 percent, unknown as to why a GPS 

reading was not obtained. Hence, by 

doubling the enumerator costs obtained for 

the eleven feedback forms having a reason, 

an estimated total cost of $89 was obtained. 

A more accurate cost could have been 

determined if more data were available. 

 As far as additional WA FO staff 

expenses, a statistician spent one hour 

preparing training materials and an 

additional two hours in training the 

enumerators (six sessions at twenty minutes 

each). This calculates out to a total of 3 

hours (two hours for training and one hour 

for preparation). 

 One GPS receiver was not returned 

by a field enumerator. This enumerator was 

ultimately removed from service for 

performance and personnel issues. 

Although, this lost receiver is not included 

as an additional cost, the replacement cost 

will factor into the cost for next year. 

 Hence, the total expenditures for the 

research project were $6,700 dollars and 3 

hours of a WA FO statistician’s time. See 

Table 2 for a complete overview of the 

costs. 
13 

Table 2: Research Project Expenses 

Item Details Total Costs $ 

35 GPS Receivers Includes 2 spare receivers. 4,961 

Miscellaneous Supplies Batteries, paper, etc. 100 

Enumerator time (salary & benefits) 63.8 hours total for 189 operations having GPS 

readings. Average 20 minutes per operation. 780 

Enumerator Mileage 1,634 miles total for 189 operations having GPS 

readings. Average 9 miles per operation. 613 

Enumerators Training (salary & 

benefits) 20 minutes per enumerator. 130 

Estimated Additional Enumerator Costs Unsuccessful attempts at obtaining a GPS reading. 

Estimated at 254 miles and 7 hours. 89 

WA FO Staff 3 hours (preparation and training of enumerators). N/A 

Research Project Total Costs Total of $6,673 rounded to next hundred. $6,700 

* All enumerator costs were based on each enumerator’s actual time and salaries incurred. The 

average salary of the enumerators was $9.99 per hour. The average salary and benefits of the 

enumerators (using NASS’ formula of (salary · 1.0763) · 1.11) calculates to $11.94 per hour. 

Enumerator mileage costs were calculated at NASS’ reimbursable rate of 37.5 cents a mile. 

 On the benefit side, using GPS 

receivers saved the WA FO statistician 

approximately 19.1 hours that the statistician 

could spend on a reimbursable project 

and/or working on or improving upon the 

state’s agricultural statistics. 

 Using GPS receivers to acquire the 

coordinates for the sampled field did not 

adversely affect the precision of the data. 

Based on the limited analysis able to be 

conducted, the GPS receivers appear to 

provide more accurate coordinates of the 

sampled fields than the current county 

highway and DLG Map method.

 The ability of the enumerators to 

record the latitude and longitude coordinates 

at the time of the interview allowed this 

information to be provided back to the office 

at the same time the questionnaires were 

returned. All points, except for the twentytwo points noted earlier, were available in 

NASS’ system by December 21st. Based on 

the statistician’s workload, the WA FO 

could easily have had all of the latitude and 
14 

longitude coordinates in the NASS system 

by January 15th. Therefore, NASS could 

move up the due date on having these 

coordinates from March 15th to mid January. 

Hence, this provides NASS the opportunity 

to shorten the due date of the coordinates by 

60 days. 

Now, the question becomes does the 

$6,700 offset the improved accuracy of the 

sampled fields’ coordinates, the ability to

provide the data 60 days quicker, and the 

19.1 hours in statistician time saved? 

At first glance, the answer is

“maybe”. The Economic Research Service 

which funds part of the ARMS Program 

would have to decide if this improved 

accuracy is worth additional funding, which 

goes beyond the scope of this report. 

Being able to provide the coordinates 

to ERS sixty days earlier is not helpful to

them since the coordinates are not useful 

without the survey data. However, this 

earlier date does change the DLG Map 

process from a post-survey activity to a task 

that can be accomplished during the survey.

Hence, there would be one less post-survey 

activity that would need to be completed

before closing out the survey. 

As far as the 19.1 hours saved in 

staff time, this provides the statistician with

more time to analyze data and thereby

improve the quality of the FO’s 

estimates/products or spend time working on 

reimbursable projects. 

Also, GPS receivers can be re-used 

for future years’ ARMS II and for other 

projects. For example, the North Carolina 

Field Office has been using similar receivers

for five years. Each year their cost of using 

the receivers is in enumeration expenses and

a supply of batteries. Hence, the initial startup costs can be spread out over time. This is

good news since the ARMS II is conducted 

yearly, assuming the State is in the 

operational program each year. If the WA 

FO were to conduct another ARMS II and 

the targeted fields’ coordinates needed to be 

obtained, the cost would be around $2,035. 

The $2,035 projected cost was determined 

by summing the $1,600 of enumerator 

expenses, the $100 in miscellaneous 

supplies, $150 for a replacement GPS 

receiver and adding a lofty 10 percent rate of 

inflation. Table 3 shows the cost per year 

and the total cost spread out over 4 years. 

Years 2, 3 and 4’s costs were calculated by 

assuming the same sample size, similar 

sample dispersion, and includes training 

expenses, replacement GPS receiver, field 

enumerator costs, mileage costs, 

replacement batteries, miscellaneous 

expenses, and a 10 percent rate of inflation. 

Table 3: Projected Costs of Using 

GPS Receivers in the WA FO 

for ARMS II. 

Year

Total cost ($) 

per Year 

Total costs ($) 

spread out over 

number of years.

1 6,700 6,700

2 2,035 4,370

3 2,240 3,660

4 2,465 3,360

Hence, using the receivers over two 

years (for ARMS II only) would spread out 

the average cost per year to $4,370. Over 

three years the cost would be spread out to 

$3,660 a year, and so on. In year five (not 

shown in Table 3), it is predicted that some

receivers may need to be replaced. 

At the same time, the savings in staff 

time would average 19.1 hours a year for a 

total savings of 76.4 hours of staff time over 

the four years. 

The bad news is that for 2006 the 
15 

WA FO is not selected in the part of ARMS 

II that requires the coordinates of targeted 

fields to be recorded. This does hinder the 

ability to spread the initial start-up costs 

over time. However, the Washington Field 

Office and the Research and Development 

Division are investigating other ways to use 

the GPS receivers. Surveys such as the 

Wheat Objective Yield Survey, June Area 

Survey, and a reimbursable Fruit Tree 

Survey are all being investigated. 

 All expenditures and benefits are 

based on the research conducted in 

Washington. The average miles and time 

spent to get to the sampled fields in other 

states may vary, depending upon the size 

and contiguousness of each farm. 

 During the study, a suggestion was 

made about using state-GPS atlases in place 

of DLG Map for those cases where the 

enumerators had to mark the sampled fields 

on county highway maps. After the county 

highway maps have been returned to the 

office, the statistician would determine the 

best locations using the GPS atlas that 

represent the marks on the county highway 

maps and finally record the appropriate GPS 

coordinates. Hence, NASS would no longer 

need the DLG Map software. Feasibility of 

this suggestion would require additional 

investigation.

7. NASS’ NEXT GPS STEP 

The research project showed that the 

use of GPS receivers for ARMS II improved 

data quality and saved office staff hours. 

Hence, recommend implementing the use of 

GPS receivers for ARMS II. The county 

highway map process would continue for 

those instances when the fields are 

inaccessible or the GPS receivers fail to 

acquire coordinates. 

8. CONCLUSION - FUTURE OF 

USING GPS RECEIVERS IN 

NASS 

 Using Global Positioning System 

receivers to obtain latitude and longitude 

coordinates forms the basis for linking 

multiple data sources based on physical 

location of a land area. This practice, 

commonly called geo-coding, is becoming 

an increasingly popular and powerful way to 

link a variety of data sets to conduct very 

sophisticated data analyses that otherwise 

would not be possible. 

 In the summer of 2005, the 

Washington Field Office and the Research 

and Development Division will conduct two 

additional research studies involving GPS 

receivers. The first research study pertains to 

the Wheat Objective Yield Survey. The 

study focuses on the enumerators’ 

perception of the usefulness of GPS 

receivers in assisting them in returning to a 

particular location in an operator’s winter 

wheat field. The second research study 

pertains to the June Area Survey. The study 

will obtain the enumerators’ perspective on 

using GPS receivers to help locate a 

particular land area to conduct their 

enumeration of the June Area Survey. 

 Hence, the Research and 

Development Division and the Washington 

Field Office will continue to investigate 

additional opportunities in utilizing GPS 

receivers, thereby shortening the time frame 

to realize a positive return on investment.
16 

Appendix A 

The Page of the ARMS II Questionnaire where Enumerators Record the 

Latitude and Longitude Coordinates of the Sampled Fields. 
17 

CONCLUSION 

LOCATION OF SELECTED FIELD 

1. I need to locate the selected field of winter wheat on 

 this map. COUNTY NAME 

OFFICE USE 

COUNTY FIPS 

CODE 

What county is the selected winter wheat field in? 0010 

Field description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

ASK FOR WASHINGTON ONLY LATITUDE LONGITUDE

Field location. . . . . . . . . . . . . . . . . . . . . . . . . . . N 

0054 

___ ___. ___ ___. ___ ___ W

0055 

___ ___ ___. ___ ___. ___ ___

 d d m m s s d d d m m s s 

2. [ENUMERATOR ACTION: 

Mark map to indicate where the selected winter wheat field is located. Be sure the “X” marked on map is in county identified above.] 

3. We will need additional information to complete this study. We will contact you in February or March, 2005, to collect it. I’ll call you then to set up a time that is good for you. 

CODE 

4. Would you like to receive a copy of the results of this survey in the mail? 

(Results will also be available on the Internet at http://www.usda.gov/nass/ & http://www.ers.usda.gov/.). . . . . . . . . . . YES = 1

0099 

RECORDS USE 

5. [Did respondent use farm/ranch records to report---] CODE 

a. [fertilizer data?]. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . YES = 1 0011 

 b. [pesticide data?]. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . YES = 1 0012 

 c. [majority of this expense data?]. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . YES = 1 0013 

1 OPERATOR/MANAGER 

2 SPOUSE 

3 ACCOUNTANT/BOOKKEEPER CODE 

RESPONDENT. . . . . . . . . . . . . . . . . . . . . 

4 OTHER 

8 OFFICE HOLD 

9 PARTNER 

. . . . . . . . . . . . . . . . . . . . . . . . . . . 

0101 

 Respondent’s name 

 [f code 3, 4, or 9]. . . . . . . . . . . . ________________________________________ 

Phone. . . . . . . . . . . . . . . . . . . . . ( ) ________________________________

MILITARY TIME 

 H H M M 

0005 

ENDING TIME[MILITARY]. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ___ ___ ___ ___ 

MM DD YY 

0007 

DATE. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . __ __ __ __ 04

ENUMERATOR ID 

ENUMERATOR NAME ___________________________________________________________________________________ 0098 
18 

Appendix B 

Enumerator - GPS Receiver Usage Form
19 

Agricultural Resource Management Survey - Phase II 

Global Positioning System Pilot Project 

Enumerator - GPS Receiver Usage 

 

Enumerator ID: __________________ 

Sequence Number: __________________ 

1. Were you able to access the sampled field and record lat/long 

coordinates with the GPS receiver? (Check one.) 

~ Yes = 1

~ No = 2 If No, then go to Question 4. ± Enter 

Code

9000

2. What (if any) additional TIME was needed to reach the sampled field 

(include obtaining any directions from the operator) and record the 

lat/long coordinates using the GPS device? 

{To avoid double counting time, if you are visiting more than one 

field, only count the time to the first field and then count the time 

from the first field to the second field on a separate form.} 

 

Hours Minutes

9100 9200

 3. What (if any) additional mileage was needed to reach the sampled 

field? 

{To avoid double counting mileage, if you are visiting more than one 

field, only count the mileage to the first field and then count the 

mileage from the first field to the second field on a separate form.} 

 

 Miles 

 

9300

Over ±
20 

4. Were any problems encountered? (Include using the GPS receiver, 

 accessing the field, etc.) If yes, please explain:

9400
21 

Appendix C 

DLG Map-Time Keeper Form
22 

DLG Map Time Keeper Form

Name: _____________________ 

Job Series: _____________________ 

To compare the Global Positioning System Method of obtaining the lat/long 

coordinates with the current method of using county maps and DLG Map, please 

record the amount of time you spend locating the Xs and sequence numbers on 

the county maps and plotting the location using the DLG Map software. Also, 

please include any additional time used to overcome any problems, (An X without 

a corresponding sequence number, wrong sequence number, missing county 

map, etc.)

 

Date Start Time Stop Time 

Number of 

Sequence No.’s 

Completed

Total Time
23 

Comments & Problems Encountered: