I know I'm coming late to this, but ... > > Is someone able to suggest to me a transformation to overcome the > > problem of heterocedasticity?
It is not usually useful to worry about this. In my experience, the gain in efficiency from using an essentially ideal weighted analysis vs. an approximate unweighted one is usually small and unimportant (transformation to simplify a model is another issue ...). Of far greater importance usually is the loss in efficiency due to the presence of a few "unusual" extreme values; have you carefully checked to make sure that none of the large sample variances you have are due merely to the presence of a small number of highly discrepant values? -- Bert Gunter Genentech Non-Clinical Statistics South San Francisco, CA "The business of the statistician is to catalyze the scientific learning process." - George E. P. Box ______________________________________________ [email protected] 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.
