[R] lm() and post hoc test

[nutini.francesco at gmail.com]

Dear Alex,
I have read your question about post-hoc test:

"Let's assume that according to Anova(lm(y~a*b, data=d)) the a:b interaction is significant, and I would like to know if there are specific combinations of a and b levels that differ from the control group. Are there any caveats against simply looking at the p-values in the output generated by summary(lm(y~a*b,data=d))? The documentation for summary.lm says nothing about multiple comparison correction, so I assume I need to do that myself, is that correct?"

I have the same problem about the interpretation of command "summary", and generically about the finest post-hoc test for implemented model with the code "lm()". I think that R-help is quite insufficient...
Which command did you use normally?

Thanks a lot,

Francesco Nutini