Best (but oft-forgotten) practices: sample size and power calculation for a dietary intervention trial with episodically consumed foods.

ABSTRACT: Dietary interventions often target foods that are underconsumed relative to dietary guidelines, such as vegetables, fruits, and whole grains. Because these foods are only consumed episodically for some participants, data from such a study often contains a disproportionally large number of zeros due to study participants who do not consume any of the target foods on the days that dietary intake is assessed, thus generating semicontinuous data. These zeros need to be properly accounted for when calculating sample sizes to ensure that the study is adequately powered to detect a meaningful intervention effect size. Nonetheless, this issue has not been well addressed in the literature. Instead, methods that are common for continuous outcomes are typically used to compute the sample sizes, resul

SUBMITTER: Zhang W 

PROVIDER: S-EPMC7528564 | biostudies-literature | 2020 Oct

REPOSITORIES: biostudies-literature