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United States Department of Agriculture

Agricultural Research Service

Title: What's Behind the Numbers? Statistical Sampling

Authors
item Holden, Joanne
item Pehrsson, Pamela
item Perry, Charles - NASS
item Haytowitz, David

Submitted to: National Nutrient Databank Conference
Publication Type: Abstract Only
Publication Acceptance Date: May 23, 2006
Publication Date: September 18, 2006
Citation: Holden, J.M., Pehrsson, P.R., Perry, C., Haytowitz, D.B. What's behind the numbers? statistical sampling. National Nutrient Databank Conference, September 18-20, 2006, Hawaii.

Technical Abstract: Objective: The Nutrient Data Laboratory (NDL), USDA implemented the National Food and Nutrient Analysis Program (NFNAP) to obtain nationally representative estimates of the critical nutrients in highly consumed U.S. foods. The NFNAP is based on a statistically based sample design to identify locations and brands for product collection and analysis. Other sources of high quality data (food industry, scientific literature, other government agencies, and standard recipes and algorithms) not based in this rigorous sampling approach complement NFNAP data in the USDA National Nutrient Databank System. Materials and Methods: The sampling design employed a three-stage sample selection process based on demographics and food products: 1) selection of counties; 2) grocery stores selected within those counties; and 3) specific food products were purchased for nutrient analyses. Current Census regions, divisions and states in the Stage 2 allow a self'weighting sample of food products from each region that is also geographically dispersed across United States. The number of food brands or types collected is based on its contribution of critical nutrients to intake and known or expected variability of those nutrients. Selection of brands of products is based on market share data, in weight consumed. Results: The general approach ensures the resulting nutrient estimates for foods are representative of the average nutrient content of foods consumed by the U.S. population. Over 1000 foods have been analyzed for over 100 nutrients since NFNAP's inception. Significance: These nationally representative data provide a foundation for nutrition research, food policy development, and nutrition education strategies and are critical in monitoring the public health status. Funding: USDA and NIH, Agreement No. Y1CN5010.

Last Modified: 9/23/2014
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