R's manova is not intended to handle `nested unbalanced data': it cross-references ?aov, which says the unbalanced part, and ?manova says the nested part.
On Mon, 5 Jan 2004, Oliver Bossdorf wrote: > Hi, > > I have a nested unbalanced data set of four correlated variables. When I > do univariate analyses, my factor of interest is significant or > marginally significant with all of the variables. Small effect size but > always in the same direction. If I do a MANOVA instead (because the > variables are not independent!) then my factor is far from being > significant. How does that come about? > > I have found a mention of a so-called Rao's paradox, which seems to deal > with exactly this phenomenon. Does anyone know more about it, e.g. a > reference? > > The next strange thing is that if do the MANOVA in R, then both > hypothesis and error degrees of freedom are multiplied by the number of > variables. When I do it in SAS, however, only the hypothesis d.f. are 4 > x univariate, while the error d.f. are as in univariate, minus 3. This > is irritating, in particular since no indication is given in the > handbooks as to how degrees of freedom are calculated in a MANOVA? Can > anyone tell me more about this? Are there different philosphies that are > responsible for the differences between R and SAS? > > I would be grateful for any help. > > Regards, Oliver > > ______________________________________________ > [EMAIL PROTECTED] mailing list > https://www.stat.math.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html > > -- Brian D. Ripley, [EMAIL PROTECTED] Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/ University of Oxford, Tel: +44 1865 272861 (self) 1 South Parks Road, +44 1865 272866 (PA) Oxford OX1 3TG, UK Fax: +44 1865 272595 ______________________________________________ [EMAIL PROTECTED] mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
