sum of squares

[array chip <arrayprofile@yahoo.com>]

Hi, 

for balanced 2-way ANOVA, type I SS should be equal to
Type III SS, this can be seen in the help page for
summary.aov() as well. However, with the following
simple example, I get different type I and III SS. can
anyone advise?

y<-rnorm(16,10,3)
a<-c(rep(0,8),rep(1,8))
b<-c(rep(0,4),rep(1,4),rep(0,4),rep(1,4))
summary(aov(y~b*a),ssType=1)
summary(aov(y~b*a),ssType=3)

Thanks




                
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