Appendix A. 
Statistical Methodology 
THE SURVEY POPULATION 
Sample Design 
The target population for the 2013 Farm and Ranch 
Irrigation Survey (FRIS) was composed of all farms 
irrigating in the reference year 2013. From the 2012 
Census of Agriculture, 197,456 records were 
identified for the U.S. level FRIS population on the 
basis of having irrigation activity on their farm or 
ranch. This excluded 1,283 institutional, research, or 
experimental farms from the total number of 
irrigators that reported in the 2012 census. 
The FRIS sample was a State level sample and 
drawn for all 50 States. This sample design targeted 
a U.S. level sample size of 35,000. A certainty 
stratum, with farms selected with probability one, 
was included in each State to ensure that the major 
irrigators in each State were sampled. The remaining 
strata were sampled systematically by acreage. The 
stratification boundaries varied among the States and 
were dependent on the distribution of total acres 
irrigated within the State. The stratified design 
ensured that the sample was reflective of the FRIS 
population and achieved the appropriate coefficients 
of variation (CV) levels at both the U.S. and State 
levels. 
The final national sample size was 34,966 farms; 
2,095 of these farms were selected from the certainty 
strata and the remaining 32,871 farms were 
systematically selected from the noncertainty strata. 
Table A provides the State sample counts for FRIS, 
including acres associated with those counts, final 
reports processed and tabulated both unexpanded 
and expanded, and 2012 census counts. 
DATA COLLECTION 
Method of Enumeration 
The 2013 Farm and Ranch Irrigation Survey was 
conducted primarily by mail. Data were also 
collected by Electronic Data Reporting (FDR) via 
the Internet, telephone enumeration, and personal 
enumeration. Enumeration methods used in the 2013 
survey were similar to those used in the 2008 survey. 
Report Form 
A single 20-page report form was created to 
consolidate what was collected on two report forms 
in the 2008 ERIS (the 2008 ERIS and the 2008 
Horticultural Irrigation Survey). This combined 
report form was used to collect irrigation data from 
farm and ranch operators and horticultural producers. 
The report form was mailed to all the producers in 
the FRIS sample that reported irrigation in the 2012 
Census of Agriculture. See Appendix B for a copy of 
the report and instruction booklet and also for 
information regarding changes between the 2008 and 
2013 forms. 
Report Form Mailings and Respondent 
Foiiow-up 
The initial mailout took place in January 2014. Mail 
packets were mailed to approximately 31,300 farm 
and ranch operations, including horticultural 
operations. The initial mail packets included a 
labeled report form, an instruction booklet, a letter 
requesting a prompt response, and a return envelope. 
Mailout packet preparation, initial mailout, and one 
follow-up mailing to nonrespondents were handled 
by the U.S. Census Bureau’s National Processing 
2012 Census of Agriculture Appendix A A - 1 
USDA, National Agricultural Statistics Service 
