摘要：In this commentary, we discuss the problem of estimating the proportion of the population at risk of a dietary deficiency. Ideally, we would need an estimate of the proportion of individuals whose intake is below their requirement. This would require knowledge about the joint distribution of intakes and requirements in the population. In lieu of information about the joint distribution of intakes and requirements, following Beaton (1993) we argue that it may suffice to know the mean of the requirement distribution together with the distribution of usual intakes. The proportion of individuals with intakes below the mean requirement for the population gives a good approximation to the proportion of individuals with intakes below their requirements, if certain assumptions hold. Those assumptions are: (a) nutrient requirements and usual intakes are independent, (b) the distribution of requirements is symmetric, and (c) the between-individual variance of requirements is small relative to the between-individual variance in intakes.
