Number of days of food intake records required to estimate individual and group nutrient intakes with defined confidence
1987
Basiotis, P.P. | Welsh, S.O. | Cronin, F.J. | Kelsay, J.L. | Mertz, W.
Food intake records for 365 consecutive days of a research study conducted by the U.S. Department of Agriculture's Beltsville Human Nutrition Research Center were used to determine the number of days of food intake records needed to estimate "true" average nutrient intakes for 29 individuals (13 males and 16 females) and groups of individuals with a given degree of statistical confidence or precision. Precision is defined as X-day average intake being within 10% of the "true average" intake for the individual or the group 95% of the time. True average intake was defined as the 365-day average for individuals or groups. The average number of days required to estimate true average food energy, iron and vitamin A intake with defined confidence were: food energy averaged 31 days and vitamin A averaged 433. This was consideralby higher than the number of days needed to estimate mean nutrient intake for this group; however, fewer days would be need for larger groups.
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