[R] Tukey post hoc test for testing interaction between two or more predictors

[Nicola Spotorno]

Hi everyone,

I woudl like to apply a Tukey post hoc after a repeated measure ANOVA. I 
followed the suggestions  that I found in this  help -list  especially 
this one:

/[R] Tukey HSD (or other post hoc tests) following repeated measures ANOVA

You want to use lme() in package nlme, then glht() in the multcomp package.
This will give you multiplicity adjusted p-values and confidence intervals.

## Example
require(MASS)         ## for oats data set
require(nlme)         ## for lme()
require(multcomp)  ## for multiple comparison stuff

Aov.mod <- aov(Y ~ N + V + Error(B/V), data = oats)
Lme.mod <- lme(Y ~ N + V, random = ~1 | B/V, data = oats)

summary(Aov.mod)
anova(Lme.mod)

summary(Lme.mod)
summary(glht(Lme.mod, linfct=mcp(V="Tukey")))

HTH, Mark.

/My problem is that in my study I want to test the interactions among 
different levels of two predictors. Considering oats dataset in MASS 
package how can I test the contrast between one level of the variable V 
(for example, Victory) and one level of the variable N(for example 0.0cwt)?

Thank you very much for your help.

Nicola