[R-lang] MANCOVA in R

[Bruno Estigarribia]

Hello,

I posted this to the general R list but got no replies. I am not sure this
is appropriate for r-lang: the data ARE linguistic but the question is
general. Apologies if this is inappropriate.

I have subjects in 4 groups: X1, X2, X3, X4. There are 33 subjects in 
group X1, 35 in X2, 31 in X3, and 46 in group X4. I have 7 continuous 
response variables (actually integers, they are frequencies of functional
morphemes, approximately normal) measured 
for each subject: Y1 to Y7, and two continuous covariates C1, C2 (they 
are both integers).
I want to perform all pairwise comparisons for each response variable 
between groups. I have searched for a way to do a MANCOVA in R to no 
avail. I am familiar with summary.manova, and with Venables & Ripley 
"Modern Applied Statistics With S" and Everitt's "An R and S-Plus 
Companion to Multivariate Analysis". However, I am neither a 
statistician nor a programmer so I am finding it hard to figure this 
out. Can summary.manova be adapted to use covariates? What is the impact 
of the unbalanced design? Can I adjust for multiple comparisons?
Thank you

Bruno Estigarribia
UNC Chapel Hill