[R] Orders of terms in formulae

Simon Wotherspoon Simon.Wotherspoon at utas.edu.au
Tue Jan 21 00:52:03 CET 2003


Hi,
	Given that R reports Type I sums of squares, isn't it a bit anachronistic
that it re-orders terms in formulae?

> d <- expand.grid(y=rnorm(8),
+             A=factor(c(1,2)),
+             B=factor(c(1,2)),
+             C=factor(c(1,2)))
> summary(aov(y ~ A+B+A:B+C,data=d))
            Df    Sum Sq   Mean Sq   F value Pr(>F)
A            1 8.294e-34 8.294e-34 1.027e-33      1
B            1 3.961e-33 3.961e-33 4.904e-33      1
C            1 3.980e-34 3.980e-34 4.927e-34      1
A:B          1 1.294e-32 1.294e-32 1.601e-32      1
Residuals   59    47.658     0.808

Or have I missed the point?

Simon.
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