Check this out: http://www.rforge.net/doc/packages/NCStats/compSlopes.html
However, it looks like one need to install NCStats (http://www.rforge.net/NCStats/files/). Or is there a more "mainstream" method of running multiples comparisons among slopes? Dimitri On Sat, Oct 30, 2010 at 1:20 PM, Alex Bokov <bo...@uthscsa.edu> wrote: > 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. > > ______________________________________________ > R-help@r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. > -- Dimitri Liakhovitski Ninah Consulting www.ninah.com ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
