R convenience function to estimate intra-class correlations (ICCs) from linear mixed-effect models (supports lme4 package).
Usage:
estICC(model)
where model is an lmer object. Returns a vector of variance components and ICC estimates. R code includes an example.
See the companion paper and our tutorial for building lmer models.
Formula for calculating ICCs taken from Raudenbush and Bryk (2002):
Raudenbush, S. W., & Bryk, A. S. (2002). Hierarchical linear models: Applications and data analysis methods (Vol. 2). Sage.