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Asked by 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?

Answer by Shashank Prasanna
on 3 Apr 2014

Accepted answer

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:

http://www.mathworks.com/help/stats/fitlme.html

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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