[R] Syntax error in using Anova (car package)

[Fox, John]

Dear Angelo,

I'm afraid that this is badly confused. To use Anova() for repeated measures, the data must be in "wide" format, with one row per subject. To see how this works, check out the OBrienKaiser example in ?Anova and ?OBrienKaiser, or for more detail, the R Journal paper at <{http://journal.r-project.org/archive/2013-1/RJournal_2013-1_fox-friendly-weisberg.pdf>.

I hope this helps,
 John

-----------------------------------------------
John Fox, Professor
McMaster University
Hamilton, Ontario, Canada
http://socserv.socsci.mcmaster.ca/jfox/



> -----Original Message-----
> From: angelo.arcadi at virgilio.it [mailto:angelo.arcadi at virgilio.it]
> Sent: Wednesday, November 25, 2015 11:30 AM
> To: r-help at r-project.org
> Cc: Fox, John
> Subject: Syntax error in using Anova (car package)
> 
> 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
> 
> 
> 
>