Statistical analysis of continuous outcomes from parallel-arm randomized controlled trials in nutrition—a tutorial

Randomized controlled trials (RCTs) play a fundamental role in establishing evidence on benefits of diet changes in nutrition. There is, however, little literature on how to analyze data obtained from such trials. This tutorial provides a detailed introduction to the statistical analysis of parallel-arm RCTs in nutrition by means of modern statistical methodology, i.e., analysis of covariance and linear mixed models are informed using specific information about the trial design. Focus will be on understanding how the trial design and possibly other aspects of the trial influence the subsequent statistical analysis. All steps of the statistical analysis will be covered and a practical example is also provided.