John, In addition to 'VarCorr(nlme) and VarCorr(Matrix)', you could also try 'varcomp' function in the 'ape' package.This requires an 'lme' class of file, from the 'nlme package as input.It additionally gives the options to scale the components by normalizing them (both cumulatively and in total). I hope this helps, John John Sorkin Wrote----- Could someone identify a function that I might use to perform a components of variance analysis? In addition to the variance attributable to each factor, I would also like to obtain the SE of the variances. Thank you, John John Sorkin M.D., Ph.D. Chief, Biostatistics and Informatics Baltimore VA Medical Center GRECC and University of Maryland School of Medicine Claude Pepper OAIC University of Maryland School of Medicine Division of Gerontology Baltimore VA Medical Center 10 North Greene Street GRECC (BT/18/GR) Baltimore, MD 21201-1524 410-605-7119 -- NOTE NEW EMAIL ADDRESS: jsorkin at grecc.umaryland.edu