Nature of Variation in Diet

Walter Willett

in Nutritional Epidemiology

Third edition

Published in print November 2012 | ISBN: 9780199754038
Published online January 2013 | e-ISBN: 9780199979448 | DOI:

Series: Monographs in Epidemiology and Biostatistics

Nature of Variation in Diet

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This chapter provides a conceptual background regarding sources of variation in diet for the novice to this field and also assembles data on dietary variation that may be of use to the serious investigator. The daily variation in nutrient intake among free-living subjects has consistently been found to be large, although the degree of variation differs greatly according to nutrient. The ratio of within-person to between-person variation is usually substantially greater when the nutrient is expressed in relation to energy intake (energy-adjusted). Measurements of dietary intake based on a single or small number of 24-hour recalls per subject can provide an accurate estimate of the mean for a group, but the standard deviation will be greatly overestimated. Furthermore, measurements of association in epidemiologic studies, such as correlation and regression coefficients and relative risks, are substantially weakened, possibly to the point of being undetectable.

Keywords: nutrition; dietary variation; nutrient intake; energy intake; epidemiologic studies

Chapter.  7487 words.  Illustrated.

Subjects: Medical Statistics and Methodology

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