[R] Anohter anova.mlm problem
Bela Bauer
bela_b at gmx.net
Wed Jun 15 09:59:41 CEST 2005
Hi,
yet another anova.mlm problem - it doesn't seem to end.
This time, I have a setup with a few within-subject factors and a
between-subject factor (SGROUP). Consider the most simple case with only one
within-factor (apo):
> mlmfit0 <- lm(data.n ~ 0 + SGROUP)
> mlmfit1 <- lm(data.n ~ 1 + SGROUP)
> anova(mlmfit1,mlmfit0,test="Spherical",M=~hemi,X=~1)
Analysis of Variance Table
Model 1: data.n ~ 1 + SGROUP
Model 2: data.n ~ 0 + SGROUP
Contrasts orthogonal to
~1
Contrasts spanned by
~hemi
Greenhouse-Geisser epsilon: 0.6829
Huynh-Feldt epsilon: 0.7127
Res.Df Df Gen.var. F num Df den Df Pr(>F) G-G Pr H-F Pr
1 22 0.54295
2 22 0 0.54295 Inf 0 44
Warning messages:
1: NaNs produced in: pf(q, df1, df2, lower.tail, log.p)
2: NaNs produced in: pf(q, df1, df2, lower.tail, log.p)
3: NaNs produced in: pf(q, df1, df2, lower.tail, log.p)
Now, those G-G and H-F epsilons it gives me are correct (at least G-G, the
H-F seems to be affected by the R vs SAS difference in the calculation). But
whatever happened to everything else?
I've played around with the source in mlm.R, and it looks to be as though
the problem is related to this:
https://stat.ethz.ch/pipermail/r-devel/2005-April/032925.html
Is there a solution to this problem? Am I doing something wrong? The data
looks like this:
> hemi
[1] 1 1 1 1 1 1 2 2 2 2 2 2 3 3 3 3 3 3
Levels: 1 2 3
> SGROUP
[1] 2 2 2 2 2 2 1 1 1 1 2 2 2 1 1 1 2 1 1 1 2 1 2 1
Levels: 1 2
> dim(data.n)
[1] 24 18
It works fine with the univariate analysis (aov())...
Thanks again,
Bela
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