Dear list members,
I am getting an error while performing a repeated measures MANOVA using the
Anova function
of the "car" package. I want to apply it on the results of an experiment
involving 19 participants,
who were subjected to 36 stimuli, each stimulus was repeated twice for a total
of 72 trials
per subject. Participants had to adjust two parameters of sounds, Centroid and
Sound_Level_Peak,
for each stimulus. This is the head of my dataset (dependent variables:
Centroid and
Sound_Level_Peak; independent variables: Mat (6 levels) and Sh (2 levels)).
> head(scrd)
Subject Mat Sh Centroid Sound_Level_Peak
1 Subject1 C DS 1960.2 -20.963
2 Subject1 C SN 5317.2 -42.741
3 Subject1 G DS 11256.0 -16.480
4 Subject1 G SN 9560.3 -19.682
5 Subject1 M DS 4414.1 -33.723
6 Subject1 M SN 4946.1 -23.648
Based on my understanding of the online material I found, this is the procedure
I used:
idata <- data.frame(scrd$Subject)
mod.ok <- lm(cbind(Centroid,Sound_Level_Peak) ~ Mat*Sh,data=scrd)
av.ok <- Anova(mod.ok, idata=idata, idesign=~scrd$Subject)
I get the following error
Error in check.imatrix(X.design) :
Terms in the intra-subject model matrix are not orthogonal.
Can anyone please tell me what is wrong in my formulas?
Thanks in advance
Best regards
Angelo
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