Have you ever wondered what makes a census different from a survey? At USDA’s National Agricultural Statistics Service, we conduct both censuses and surveys. The difference is in the totality of the respondents who receive a questionnaire.
In a census, we gather information from every member of a population. For example, the Census of Agriculture, conducted every five years, is a complete count of every known and potential ag operation and producer in the United States. When NASS conducts a census, we send a questionnaire to every producer who qualifies to be included in the effort.
In a survey, we gather information from a sample representing the population. Everyone who qualifies will not receive a questionnaire, but rather a selection of respondents who best represent the population defined in the survey will receive it.
At NASS, we select the sample from our database list. The database includes all known agricultural establishments. Using modern survey and sampling methodology, NASS defines a population for a specific survey and then pulls representatives who meet those criteria from the database. In order to produce accurate statistics, sampling for a survey can be a complex endeavor. NASS updates and maintains the database continually to always have the best respondent sample list possible for accurate statistics.
Every census is a survey, but not every survey is a census. Although every producer is not included in NASS surveys, the results are statistically accurate. The accuracy is measured and provided for most of the survey results. If you are interested in learning more about the methodology NASS uses in surveys, USDA - National Agricultural Statistics Service - Methodology and Quality Measures is a good place to start. For census methodology, refer to the USDA - National Agricultural Statistics Service - Census of Agriculture - Frequently Asked Questions 2022.