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Unresolved Matched 

Records in CaptureRecapture Methodology 

Andrea C. Lamas 

Denise A. Abreu 

Shu Wang 

Daniel Adrian 

Linda J. Young 

USDA

National Agricultural Statistics Service 

2013 FCSM Research Conference 

November 6, 2013 
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Contents 

 Overview of NASS 

 Census of Agriculture 

 June Area Survey 

 Census Bureau 

 Dual System Estimation 

 Unresolved Records 

 Conclusions 
 

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National Agricultural Statistics Service 

(NASS) 

 NASS conducts hundreds of surveys 

including the Census of Agriculture 

 Prepares reports covering every facet of 

United States agriculture 

– For example: 

 Production and food supplies 

 Prices paid and received by farmers 

 Farm income and finances 

 Number of farms and land in farms 
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Farms in the United States 

 A farm is any place from which $1,000 or more 

of agricultural products were produced and sold 

or normally would have been sold during the 

year

– Examples, some special cases: 

 Christmas trees 

 "government payment" farms 

 "pasture only" farms (at least 100 acres) 

 nurseries and greenhouses 

 exotic livestock 
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Census of Agriculture 

 Conducted every 5 years (years ending in 2 and 7) 

 Count of all US Agricultural operations ($1000 or more in 

sales) 

 Collects information on agricultural operations’ commodities 

and operator demographics 

 Only source of uniform, comprehensive agricultural data for 

every county or county equivalent in the U.S. 

 Starts with list-based frame 

– Census Mail List (CML) 

 Primarily mail data collection 
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Sources of Error 

 Under-coverage 

– Incompleteness of the list 

 Not all agricultural operations appear on the Census 

Mail List 

 Non-response 

– Not all agricultural operations on the Census Mail 

List respond 
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Sources of Error (cont) 

Errors in Census reporting 

 Misclassification of Census non-farms 

– Non-farms classified as farms 

 Includes a subset of non-farms 

 Misclassification of Census farms 

– Farms classified as non-farms 

 Omits a subset of farms 
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Sources of Error 

U.S. Farms

U.S. Agricultural Operations

Operations on CML

Census Respondents

Census Farms
June Area Survey (JAS) 

 Area-based survey 

 Conducted annually 

 Theoretically complete sampling frame 

– No overlap or gaps 

 Sample rotation scheme used every year 

– 20% of the sample replace every year 

– Sample rotations remain for 5 years 

 Stratified sample based on land-use and percent of 

cultivation 

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NASS Area Sampling Frame 
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NASS Area Frame 

 Segments of land sampled 

 Sampled segments divided 

into tracts representing 

unique land operating 

arrangements 

 In-person interviewers 

 All tracts pre-screened and 

classified as: 

– Agricultural 

– Non-agricultural 

 With potential 

 With unknown potential 

 With no potential 

 Crop and livestock 

information is collected only

on the operations classified 

as agricultural 
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Census Bureau Methods 

 U.S. Census Bureau studied a capturerecapture adjustment method for 2000 

Decennial U.S. Census 

– Used: 

 U.S. Decennial Census 

 Accuracy and Coverage Evaluation (A.C.E.) survey 

 Methodology also used by Office of National 

Statistics (ONS) in the U.K. 
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Capture Recapture Methodology 

 Dual system estimation 

 Requires two independent surveys 

 NASS Application: 

– Goal: Want to get estimates for Census of 

Agriculture 

 Sample 1: Census of Agriculture records overlapping 

JAS tracts (not all census records) 

 Sample 2: June Area Survey tracts 
Primary Assumptions 

 Independence of the Census and JAS 

 

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Proportion of JAS farms 

captured by Census = Proportion of U.S. farms captured by Census 

– Adjusts for farms not captured by either the 

Census or JAS 
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Census Matched to JAS 

U.S. Farms 

Responded as Farms 

on Census 

JAS Farms 

JAS Farms Responding as 

Farms on Census 

U.S. Agricultural Operations 
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What Data for DSE? 

 Match Census records and JAS tracts 

– JAS tracts and CML records were brought together 

into link groups 

 Should represent the same operation 

– Link groups classified into 3 types 

 matches, possible matches and non-matches 

– Thorough staff review of possible matches 

 Matches / non-matches 

 Records kept: 

– CML respondent/non-respondent matching JAS tract 

– Farms on JAS that are not on Census Mail List 
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Unresolved Records 

 In the matched dataset, farm status based on 

the Census and the JAS agree in most cases 

– Resolved farm status 

 Some records are identified as farms (nonfarms) on the JAS and non-farms (farms) on 

the Census 

– Unresolved farm status 
2012 Census of Agriculture and JAS 

Records with Unresolved Farm Status 

CML 

Non-Farm

CML 

Farm

CML 

Non-Resp. 

NML NML 

Domain 

Non-Farm

Total

Jas Non-Farm 2,938 2,942 1,463 1,090 19,675 28,108

JAS Farm 2,354 34,415 7,835 2,013 1,439 48,056

Total 5,292 37,357 9,298 3,103 21,114 76,164

Numbers of records with unresolved farm status are highlighted. 

Subset of records with unresolved farm status were sent to 

the Regional Field Offices for manual review in an effort to 

resolve conflicts. (CML non-respondents were not 

reviewed.) 
Resolutions to Unresolved Farm Status 

Census 

Farm

Census 

Non-Farm

Totals

Both JAS and Census Correct 240 235 475

JAS Farm Status Correct 235 1268 1503

Census Farm Status Correct 2075 378 2453

Resolved By Correcting 

Matches

131 233 364

Cannot Resolve 120 162 282

Totals 2801 2276 5077
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Unresolved Records 

 Develop logistic model of the probability of an 

operation being a farm based on records with 

resolved farm status 

– Resolved farms are given a farm status value of 1 

– Resolved non-farms are given a farm status of 0 

– Normalized JAS weights are used in the model 

 Unresolved operations are given an imputed 

farm status value 

– Estimated probability of being a farm obtained from 

missing data model 
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Missing Data Model 

 Farm-level data collected on either the Census 

or JAS can be used to develop the models 

 Less information is available for the non-farms 

than for the farms 

– Limits the covariates available for model 

development 
 

Unresolved Records 

 Probability that an unresolved record is a farm 

will be reflected in a reduction of the associated 

JAS weights 

where = initial JAS weight 

 = predicted probability that a record is a farm 

 = adjusted weight that will be used in the 

 regression models 

Fi i Fi w w p

ˆ

Fi pˆ

wi

wFi

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Conclusions 

 DSE adjusts for farms not captured by either 

the Census or JAS 

 Unresolved records that cannot be resolved 

through staff review can be given an imputed 

farm status value 

 All records will be used in DSE 
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Thanks! 

Andrea Lamas 

Andrea.Lamas@nass.usda.gov