> On Nov 25, 2015, at 8:30 AM, angelo.arc...@virgilio.it wrote: > > 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?
I suspect that instead of `idesign=~scrd$Subject` that you may want `idesign=~scrd|Subject` or after experimenting with an example in ?Anova, more probably `idesign=~scrd*Subject` The `$` operator is generally not correctly used in formulas, since it would violate the scoping expectations of the package authors. It would be pulling in a vector of length nrow(scrd) from the object outside the function evaluation frame. I also question whether the repeated measures within trial might also be needed to be accounted for in the ‘idata' object and ‘idesign' formula. I’m not a real statistician, so this is based more on syntactical reasoning rather than considered statistical advice. You probably do need to be consulting a real statistician. > > Thanks in advance > > Best regards > > Angelo > > [[alternative HTML version deleted]] This is a plain text mailing list, although your current posting seems to have survived intact. > > ______________________________________________ > R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see > 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. David Winsemius Alameda, CA, USA ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see 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.
