I've forgot to cite the Games and Howell procedure, which some literature (eg in "Pairwise Multiple Comparison Procedures: A Review" [1]) referes as a good one for uneual samples and non homogeneus variance. Yet I haven't found an implementation for R...
giovanni [1] http://psycnet.apa.org/journals/bul/96/3/589.pdf 2009/11/30 G. Allegri <gioha...@gmail.com>: > This is a mixed question, between theory and practice. > I have a dataset with a continous variable grouped by a 33 levels > factor. After having log-tranformed my original data I can assume the > normality of my data but I have two strong departures from the basic > assumptions for anova and t tests: *unbalanced data* (some groups > contain ten samples, others hundreds) and *non homogenity of > variances* (tested with a kruscal test just for a qualitative > assessment). > Is it possible, and how, to make multiple comparisons when these > conditions are met? In past anaylises I've simply used the > pairwise.t.test function to do multiple t-test, but know I have to > consider the above situation... > > Thanks a lot, > giovanni > ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
