Change sum of squares type for ANOVA

Dear Michael and Michael,

I took a quick look at the Statistica website, and their definition of "types" of sums of squares doesn't appear to be the same as the common definition, which originated with SAS. As I read their materials, what they call "Type VI" sums of squares would correspond to the "Type III" tests provided by Anova() in the car package by setting type=3. 

As well, the reference to "sigma-restricted coding" in the Statistica documentation corresponds to contrasts provided by contr.sum() in R. This is important for Type III tests because it produces a row-basis for the model matrix with orthogonal effects. One way to do this is via options(contrasts=c("contr.sum", "contr.poly")). See ?Anova for more information.

I hope this helps,
 John

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John Fox, Professor
McMaster University
Hamilton, Ontario
Canada L8S 4M4
Web: socserv.mcmaster.ca/jfox

Change sum of squares type for ANOVA

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