[R] Multiple comparison and two-way ANOVA design

Andrej Kastrin andrej.kastrin at siol.net
Sun Jan 15 19:22:18 CET 2006

Dear useRs,

I'm working on multiple comparison design on two factor (2 Ã— 3 levels) 
ANOVA. Each of the tests I have tried (Tukey, multcomp package) seem to 
do only with one factor at a time.

fm1 <- aov(breaks ~ wool * tension, data = warpbreaks)
tHSD <- TukeyHSD(fm1, "tension", ordered = FALSE)

          diff       lwr        upr     p adj
M-L -10.000000 -19.35342 -0.6465793 0.0336262
H-L -14.722222 -24.07564 -5.3688015 0.0011218
H-M  -4.722222 -14.07564  4.6311985 0.4474210

I'm interested in posthoc comparisons between various levels of factor 1 
and various levels of factor 2, both at the same time.
I know that is possible in SPSS, but... is there any R solution?

Cheers, Andrej

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