Power analysis allows “to determine the sample size required to detect an effect of a given size with a given degree of confidence” (Clay Ford). Clay Ford’s vignette for Stephane Champely’s package pwr
gives some clear examples and explanations (here). For power analysis in Mixed Effect models, see this and this article. Here is my example of a power analysis for a linear model, with package pwr
, and for a mixed-effect model, with package simr
.