[R] summary.lm for post-hoc tests
Alex Bokov
bokov at uthscsa.edu
Sat Oct 30 19:20:00 CEST 2010
Let's say I've run Anova(lm(y~a*b)) and found the a:b interaction to be
significant. Now I'm interested in which specific level combinations of
a and b significantly differ from the control group. Can I use the
t-tests from summary(lm(y~a*b)) to answer that question?
I saw no mention of multiple comparison in the documentation for
summary.lm, so am I right in assuming I need to run p.adjust on the
p-values column?
Thanks.
PS: I am aware of TukeyHSD and that works fine if a and b are both
factors. However, if 'a' is numeric and I'm interested in which levels
of 'b' have a different slope from the control group, TukeyHSD cannot do
that, and I'm hoping the above can.
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