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United States Department of Agriculture
National Agricultural Statistics Service

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  NASS Surveys: The Foundation of Estimates

Probability Surveys

Most of the estimates are based on data collected from a sample of a given population. The samples are designed so that the chance, or probability, of including a particular operation in the sample is known before the survey is carried out. The sample data can be used to measure how much the survey estimates could differ from the population values. This measure of variability, due to selecting a sample rather than conducting a census is called the sampling error.

The data from a probability-based sample can then be used to make precise inferences about the population. This survey technique has distinct advantages over a census; it takes less time, costs less, and can actually be more accurate because fewer errors are made in reporting and handling the smaller quantities of data. Also, the results of the survey stand alone; they do not depend on relationships to other sets of data, such as the Census of Agriculture.

NASS employs two basic techniques to sample farmers, ranchers, and agribusinesses; area frame sampling and list frame sampling.


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Last modified: 06/17/09

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