[S] multiple comparisons in split-plot aov

Hobie Perry (hperry@forestry.umn.edu)
Thu, 09 Jul 1998 11:39:40 -0500


Hello,

I am using S-Plus 4.0/Win95.

I am using split plot designs to model repeated measures. I would like to
be able to perform multiple comparisons (multicomp).

The structure of the data frame is as follows:
response variable log(conc)
factors treatment 3 levels x 3 reps
date.factor 2 levels
plot.no 9 levels

aov(log(conc) ~ treatment*date.factor + Error(plot.no))

A sample anova table looks like this:

> summary(aovout.NO3dt)
Error: plot.no
Df Sum of Sq Mean Sq F Value Pr(F)
treatment 2 2.820660 1.410330 14.68144 0.004884396
Residuals 6 0.576373 0.096062

Error: Within
Df Sum of Sq Mean Sq F Value Pr(F)
date.factor 1 0.1040808 0.1040808 2.376247 0.1741292
treatment:date.factor 2 0.0495196 0.0247598 0.565286 0.5957730
Residuals 6 0.2628030 0.0438005

I can call for aovout.NO3dt$plot.no AND aovout.NO3dt$Within. However, the
following multicomp calls do not work.

> multicomp(aovout.NO3dt, focus="treatment")
Error in call to multicomp(): Argument focus= not matched
Dumped

> multicomp(aovout.NO3dt$plot.no, focus="treatment")
Error in terms: Missing value where logical needed: if((ndrop <-
sum(if(neg.out) ord <=
0 else ord == 0)) > 0) o <- o[ - (1:ndrop)]
Dumped

Suggestions?

Thanks in advance,
Hobie Perry

--
C. Hobart Perry				hperry@forestry.umn.edu
Department of Forest Resources		+1 612 625 5765 (voice)
University of Minnesota, St. Paul	+1 612 625 5212 (fax)
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