Linear Mixed Model Sample Size Calculations

This post outlines a Shiny app to calculate the required sample size for a two-group linear mixed model.

It uses the power.mmrm function from the longpower package (see Lu, Luo, & Chen, 2008, for more information).

The input is simplified, whereby users are limited to five time-points, the correlation matrix is a compound symmetry correlation structure that is identical for both groups, and the attrition rate is assumed to be the same for both groups.

Shiny App