[R] ANOVA for mixture experiment

S Ellison S.Ellison at LGCGroup.com
Mon Jul 15 16:18:19 CEST 2013

> But the ANOVA results is incorrect when I use
> aov.out = aov(Response~-1+x1*x2*x3).
First, this doesn't work at all. Your variables are in upper case and your data environment is not specified, so you must have done something else. I can get an answer using something like
anova(lm(Response~-1+X1*X2*X3-I(X1*X2*X3), data=d))
(I dropped the indetyerminable 3-way product explicitly)

Second, your answer differs from that listed by 'the original paper' at least partly because you have done something different from what has been done in the paper. You have asked for anova using Type I sums of squares. The paper has apparently calculated something other than a Type I sums of squares ANOVA.
Try calculating using Type 3 sums of squares using Anova from the car package. I did that using
Anova(lm(Response~-1+X1+X2+X3+I(X1*X2)+I(X1*X3)+I(X2*X3), data=d), type=3)

Then read the help page - especially the "Warning" section - for ?Anova very carefully ...

S Ellison

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