Dear all, is there a standard way to calculate a nested, unbalanced ANOVA with R? I am glad for pointers, tips, ideas. The problem that I am trying to evaluate is a comparison of (average) group sizes. The explanatory variables that I would like to include are species which are nested within families and (partly) crossed with region, i.e. some species occurr in several regions while others do not. For some species I have several estimates of average group size in a given region and, of course, not all families have the same number of species but each species only occurrs in one family. I actually went back to Splus (5.0 R2 for Sun SPARC) because Splus has the nested %in%, rsp. / which can be included in a formula, but the two models res <- aov (gs ~ fam/spe + reg) res <- aov (gs ~ fam + reg + spe) calculate exactly the same ANOVA table. Am I completely wrong or they? Is it ok instead, if I calculate aov (fam + spe + reg) but test the family in that I divid its mean square by the mean square of species to get an F-value or is this too crude? Thanks for your help. Regards, Lorenz -- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Lorenz Gygax LGygax at amath.unizh.ch; room: 36-L-40 Department of Applied Mathematics University of Zuerich-Irchel Winterthurerstr. 190; CH-8057 Zurich voice: 41-1-635-58-52 fax: 41-1-635-57-05 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.- r-help mailing list -- Read http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html Send "info", "help", or "[un]subscribe" (in the "body", not the subject !) To: r-help-request at stat.math.ethz.ch _._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._