[R] how calculation degrees freedom

[Peter Dalgaard]

Søren Højsgaard <Soren.Hojsgaard at agrsci.dk> writes:

> Along similar lines, I've noticed that the anova() function for lmer
> models now only reports the mean squares to go into the numerator
> but "nothing for the denominator" of an F-statistic; probably in
> recognition of the degree of freedom problem. It could be nice,
> however, if anova() produced even an approximate anova table which
> can be obtained from Wald tests. The anova function could then print
> that "these p-values are large sample ones and hence only
> approximate"...

I'm reasonably convinced by now that the relevant denominator is
always the residual variance, but it is happening via deep magic that
I don't quite understand... (and is quite counterintuitive to people
who are used to the traditional ANOVA decompositions in orthogonal
designs)

While we're on the subject: It would be desirable to have Wald tests
for specific terms rather than the "Type 1" (sorry, Bill) progressive
ANOVA table. Just like we already have in lme().



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