On Jun 12, 2011, at 12:50 , eldor ado wrote: > dear r community... > > it loks like i won't be able to reach homogenity of variance for my > dataset, so i end up with welch anova instead of regular anova. > documentation on this test is rather scarce, so maybe someone here can > enlighten me a bit: > > - do i understand that no two-way implementation of the welch anova > has been developed yet?
Has the THEORY been developed? For complete data, I suppose you can formulate it as a multivariate contrast test and employ Huynh-Feldt correction, but it is not quite the obvious generalization. Otherwise, formulate as a mixed model with error variance depending on treatment, but the degree-of-freedom adjustments are not implemented in lme. > - is there a post-hoc test for welch anovas implemented in R? Again, what does it mean? pairwise.t.test(..., pool.sd = FALSE, var.eq = FALSE) will do various pairwise comparison and allow simple corrections of the p value (Bonferroni and close relatives). > > thanks a lot, > lukas kohl > > ______________________________________________ > 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. -- Peter Dalgaard Center for Statistics, Copenhagen Business School Solbjerg Plads 3, 2000 Frederiksberg, Denmark Phone: (+45)38153501 Email: pd....@cbs.dk Priv: pda...@gmail.com ______________________________________________ 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.
