A semiparametric transformation approach to estimating usual daily intake distributions
A semiparametric transformation approach to estimating usual daily intake distributions
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DOI：
10.2307/2291570
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发表时间：
1996-12-01
影响因子：
3.7
通讯作者：
Fuller, WA
中科院分区：
文献类型：
--
作者：
Nusser, SM;Carriquiry, AL;Fuller, WA
膳食成分的一般摄入量分布对于制定食物政策和设计营养教育计划的人来说是重要的。一个人的膳食成分的通常摄入量是该人该成分每日摄入量的长期平均值。由于不可能直接观察个体的日常摄入量，因此有必要根据个体样本以及对个体子样本的少量每日观察来开发日常摄入量分布的估计量。个人的每日摄入量数据是非负的，而且往往非常偏斜。此外，相对于个体间变异，存在较大的日间变异，个体内变异与个体均值相关。我们提出了一种方法来估计通常的摄入量分布，允许不同程度的偏离正态分布，并认识到与一天的饮食摄入量的测量误差。估计方法包括四个步骤。首先，通过调整滋扰效应（如一周中的某一天和访谈顺序）对原始数据进行标准化。其次，每日摄入量数据转换为正态使用的组合功率和嫁接多项式变换。三分之使用正态方差分量模型，为转换后的数据构建通常摄入量的分布。最后定义了一种由正常的通常摄入量分布到原始尺度的变换。该方法适用于数据，他1985年持续调查的食物摄入量的个人和作品以及一组饮食成分，几乎每天消耗，并表现出不同的分布形状。
The distribution of usual intakes of dietary components is important to individuals formulating food policy and to persons designing nutrition education programs. The usual intake of a dietary component for a person is the long-run average of daily intakes of that component for that person. Because it is impossible to directly observe usual intake for an individual, it is necessary to develop an estimator of the distribution of usual intakes based on a sample of individuals with a small number of daily observations on a subsample of the individuals. Daily intake data for individuals are nonnegative and often very skewed. Also, there is large day-to-day variation relative to the individual-to-individual variation, and the within-individual variance is correlated with the individual means. We suggest a methodology for estimating usual intake distributions that allows for varying degrees of departure from normality and recognizes the measurement error associated with one-day dietary intakes. The estimation method contains four steps. First, the original data are standardized by adjusting for nuisance effects, such as day-of-week and interview sequence. Second, the daily intake data are transformed to normality using a combination of power and grafted polynomial transformations. Third. using a normal components-of-variance model, the distribution of usual intakes is constructed for the transformed data. Finally, a transformation of the normal usual intake distribution to the original scale is defined. The approach is applied to data from;he 1985 Continuing Survey of Food Intakes by Individuals and works well for a set of dietary components that are consumed nearly daily and exhibit varying distributional shapes.