On 17 Apr 2006 23:55:14 +0200, Peter Dalgaard <[EMAIL PROTECTED]> wrote: > Confusing nesting and nesting... > > The / operator is designed to handle cases like this > > a b > 1 1 > 1 2 > 2 1 > 2 2 > > in which the numbering of b only makes sense within a - no connection > between b=1 when a=1 and when a=2 (think group1, member1). In this > case, the interaction a:b makes sense, but a main effect of b does > not.
This makes sense. It sounds like there's no need for the "/" operator, assuming the factors are numbered appropriately. Is this correct? > It is not clear to me what B(A) is supposed to mean in Kirk's > terminology. Sounds like it could be the total sum of squares for the > b stratum, which is the effect of b ignoring a (?). SSB(A), as Kirk defines it, is "the pooled simple main effects of treatment B at each level of treatment A". Or [AB] - [A], if you prefer. I suppose my primary problem is specifying a different denominator for each level of the F test in the ANOVA. I can specify an overall error term (using "Error" in the model specification) but for the example in the book the F-test for factor A is MSA/MSB(A), while the F-test for factor B(A) is MSB(A)/MSerror. It doesn't seem like it's possible to do this using a single "aov" command; I have to run it once with each appropriate error term or do the F-test by hand. That can't be right, can it? -- Chris ______________________________________________ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html