[R] within-subject factors in lme
Gang Chen
gangchen at mail.nih.gov
Mon Aug 20 19:51:05 CEST 2007
I'm trying to run a 3-way within-subject anova in lme with 3 fixed
factors (Trust, Sex, and Freq), but get stuck with handling the
random effects. As I want to include all the possible random effects
in the model, it would be something more or less equivalent to using aov
> fit.aov <- aov(Beta ~ Trust*Sex*Freq+Error(Subj/(Trust*Sex*Freq)),
Model)
However I'm not so sure what I should do in lme. Sure
> lme(Beta ~ Trust*Sex*Freq, random = ~1|Subj, Model)
works fine, but it only models the random effect of the intercept. I
tried the following 4 possibilities:
> lme(Beta ~ Trust*Sex*Freq, random = pdBlocked(list(pdCompSymm
(~Trust-1), pdCompSymm(~Sex-1), pdCompSymm(~Freq-1), pdIdent(~1))),
Model)
> lme(Beta ~ Trust*Sex*Freq, random = pdBlocked(list(pdCompSymm(~
(Trust*Sex*Freq-Trust:Sex:Freq-1)), pdIdent(~1))), Model)
> lme(Beta ~ Trust*Sex*Freq, random = pdBlocked(list(pdCompSymm(~
(Trust*Sex*Freq-1)), pdIdent(~1))), Model)
> lme(Beta ~ Trust*Sex*Freq, random = pdBlocked(list(pdCompSymm
(~Trust-1), pdCompSymm(~Sex-1), pdCompSymm(~Freq-1), pdCompSymm(~
(Trust-1)*(Sex-1)), pdCompSymm(~(Trust-1)*(Freq-1)), pdCompSymm(~
(Sex-1)*(Freq-1)), pdIdent(~1))), Model)
but all failed with the same error message:
Error in getGroups.data.frame(dataMix, groups) :
Invalid formula for groups
What am I missing?
Saw a similar situation in the archives, but I'm still clueless about
the solution:
http://tolstoy.newcastle.edu.au/R/e2/help/07/01/8431.html
Any help would be highly appreciated.
Gang
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