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DRI DIETARY REFERENCE INTAKES: Applications in Dietary Assessment
FIGURE 4-2 Plot of usual intakes and requirements of 3,000 hypothetical individuals in a population. By counting the points that fall to the left of the 45° line where intakes equal requirements (the shaded area), the proportion of the population with inadequate intakes can be determined.
Unfortunately, collecting data on the joint distribution of usual intake and requirements, such as those presented in Figure 4-1 and Figure 4-2, is impractical because rarely is an individual's requirement known (if it were, it could be used to answer the question). Therefore, rather than observing the prevalence of inadequate intakes in the group, the prevalence can only be approximated by using other methods. The next two sections describe statistical approaches to estimating the prevalence of inadequate intakes—the probability approach (NRC, 1986) and a shortcut to the probability approach called the EAR cut-point method (Beaton, 1994; Carriquiry, 1999).
THE PROBABILITY APPROACH
The data typically available for nutrient assessment include estimated univariate distributions of usual intakes for a group of individuals and information from estimated univariate distributions of nutrient requirements of other groups that are similar to the group