Hi, I was trying to figure out how to do post-hoc tests for Two Way ANOVAs and found the following 2 approaches: a. Do pairwise t-tests (bonferroni corrected) if one finds significance with the ANOVA. Link- http://rtutorialseries.blogspot.com/2011/01/r-tutorial-series-two-way-anova-with.html b. Do TukeyHSD on an aov model Link- http://www.r-bloggers.com/post-hoc-pairwise-comparisons-of-two-way-anova/ Running the data set given in the first example in SPSS gives significant pairwise difference for Treatment and Age (Treatmen and Age were the independent variables) , while using the directions given in the first link didn't give me significant pairwise different for Treatment (only gave for Age). I have a few questions: a. Is the first method completely incorrect as hinted in the second link? b. What is the right way to do Bonferroni corrected post hoc tests for Two Way ANOVA in R? c. Does anyone know how post hoc tests for SPSS work in the case of Two Way ANOVAs (Univariate analysis)? Especially for Bonferroni corrected tests. I am new to R, so please let me know if I made a mistake in framing the question; I will try to elucidate as much as I personally can. Thanks for your help. -- View this message in context: http://r.789695.n4.nabble.com/Post-Hoc-tests-for-ANOVA-tp4646710.html Sent from the R help mailing list archive at Nabble.com.
Please look at the ?mmc example for two-way ANOVA in library(HH).
If you don't already have HH you can get it with
install.packages("HH")
library(HH)
?mmc
mmc uses the glht function in the multcomp package for its calculations
and then draws the MMC graph.
Rich
On 10/19/12, Amartya <amartya916 at gmail.com>
wrote:> Hi,
>
> I was trying to figure out how to do post-hoc tests for Two Way ANOVAs and
> found the following 2 approaches:
>
> a. Do pairwise t-tests (bonferroni corrected) if one finds significance
> with
> the ANOVA.
> Link-
>
http://rtutorialseries.blogspot.com/2011/01/r-tutorial-series-two-way-anova-with.html
>
> b. Do TukeyHSD on an aov model
> Link-
> http://www.r-bloggers.com/post-hoc-pairwise-comparisons-of-two-way-anova/
>
> Running the data set given in the first example in SPSS gives significant
> pairwise difference for Treatment and Age (Treatmen and Age were the
> independent variables) , while using the directions given in the first link
> didn't give me significant pairwise different for Treatment (only gave
for
> Age).
>
> I have a few questions:
>
> a. Is the first method completely incorrect as hinted in the second link?
> b. What is the right way to do Bonferroni corrected post hoc tests for Two
> Way ANOVA in R?
> c. Does anyone know how post hoc tests for SPSS work in the case of Two Way
> ANOVAs (Univariate analysis)? Especially for Bonferroni corrected tests.
>
> I am new to R, so please let me know if I made a mistake in framing the
> question; I will try to elucidate as much as I personally can. Thanks for
> your help.
>
>
>
>
>
> --
> View this message in context:
> http://r.789695.n4.nabble.com/Post-Hoc-tests-for-ANOVA-tp4646710.html
> Sent from the R help mailing list archive at Nabble.com.
>
> ______________________________________________
> R-help at 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.
>
Amartya: This is probably more of a statistics question than an R question. I would go with the Tukey HSD, were I you as that is its intention. Is there anyone in your organization (school, company, etc) that does statistical consulting? I have had wonderful experience working with the consulting clinic at the U of MN. If nothing else, buying a stats grad student some coffee might save you hours of headache in reading and searching message boards. Mike. On Oct 19 2012, Amartya wrote:>Hi, > >I was trying to figure out how to do post-hoc tests for Two Way ANOVAs and >found the following 2 approaches: >a. Do pairwise t-tests (bonferroni corrected) if one finds significance with>the ANOVA. >Link-http://rtutorialseries.blogspot.com/2011/01/r-tutorial-series-two-way-anova-with.html> >b. Do TukeyHSD on an aov model >Link- >http://www.r-bloggers.com/post-hoc-pairwise-comparisons-of-two-way-anova/ > >Running the data set given in the first example in SPSS gives significant >pairwise difference for Treatment and Age (Treatmen and Age were the >independent variables) , while using the directions given in the first link >didn't give me significant pairwise different for Treatment (only gave for >Age). > >I have a few questions: > >a. Is the first method completely incorrect as hinted in the second link? >b. What is the right way to do Bonferroni corrected post hoc tests for Two >Way ANOVA in R? >c. Does anyone know how post hoc tests for SPSS work in the case of Two Way >ANOVAs (Univariate analysis)? Especially for Bonferroni corrected tests. > >I am new to R, so please let me know if I made a mistake in framing the >question; I will try to elucidate as much as I personally can. Thanks for >your help. > > > > > >--View this message in context: http://r.789695.n4.nabble.com/Post-Hoc-tests-for-ANOVA-tp4646710.html>Sent from the R help mailing list archive at Nabble.com. > >______________________________________________ >R-help at r-project.org mailing list >https://stat.ethz.ch/mailman/listinfo/r-helpPLEASE do read the posting guide http://www.R-project.org/posting-guide.html>and provide commented, minimal, self-contained, reproducible code. >