The Yield Forecasting Program of NASS

The National Agricultural Statistics Service (NASS) is responsible for estimating production of most crops grown in the United States. Additionally, early season forecasts are prepared for the major crops. NASS conducts several surveys to obtain the basic data needed to fulfill this obligation. These surveys are a mix of grower interviews and objective field visits employing sophisticated survey sample designs and statistical methodology. Large surveys designed to measure acreages are used to define prescreened subsampling populations for the yield surveys. These surveys and the subsampling techniques are described, and the data collection procedures are also outlined. Summary formulas are given, and regression techniques employed in the forecasting process are discussed in detail. Each survey produces indications of prospective yield which commodity specialists must interpret to arrive at the official forecast or estimate of NASS and the USDA. This paper discusses in detail the process of producing these indications by the Summary, Estimation, and Disclosure Methodology Branch and outlines the review process used by the commodity specialists in the Crops Branch. A brief discussion of acreage estimates is included to the extent that they impact sampling and the calculation of production.