degrees of freedom for random factors in anovan

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laurie on 3 Apr 2014
Commented: laurie on 3 Apr 2014
"anovan" seems to give the same number of degrees of freedom to a factor whether it is declared as random or fixed.
I thought that random factors "cost" less degrees of freedom. At least this is what happens in regression with mixed effects.
Any clues? Is this normal behavior?

Accepted Answer

Shashank Prasanna
Shashank Prasanna on 3 Apr 2014
Laurie, anovan uses method of moments unlike in mixed-effects models which may use ML or REML. If you are interested in the latter, you may want to use:
here the degrees of freedom will be equal to n – p, where n is the number of observations and p is ONLY the number of fixed effects, not random effects.
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laurie on 3 Apr 2014
Ok, so this is a normal behavior! I thought I was doing something wrong with the model specification in anovan. Well, that's a shame. Thanks :-)

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