[R] ANOVA type III sum of squares?

John Fox jfox at mcmaster.ca
Tue Aug 13 01:20:48 CEST 2002

Dear Francois,

As Brian Ripley and Kjetil Halvorsen have pointed out, the Anova function 
in the car package will compute Type III (and, incidentally, Type II) tests 
(for both linear and generalized linear models). If you decide that you 
want Type III tests, however, be careful with the contrast coding. In 
particular, for models with interactions, the default "treatment" coding in 
R will give meaningless results.


At 01:41 PM 8/9/2002 +0000, francois klam wrote:
>I'm a neurophysiologist, and actually quite new to R. In fact, to analyse 
>the responses of my neurons, I would like to have R doing an 
>non-orthogonal ANOVA with a type III sum of squares.
>Could anybody help me?
>Thank you a lot in advance.

John Fox
Department of Sociology
McMaster University
Hamilton, Ontario, Canada L8S 4M4
email: jfox at mcmaster.ca
phone: 905-525-9140x23604
web: www.socsci.mcmaster.ca/jfox

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