[R-sig-eco] Mixed effects models with ordinal response variable
Omer Nevo
nevo84 at gmail.com
Mon Apr 23 11:54:27 CEST 2012
Hello everybody,
I have a dataset with an ordinal response of 5 levels which wish to
model on 4 potential predictors. There's a lot of repeated measurements
(of individual howler monkeys) so a mixed model is required.
I tried pretending the response was a continuous variable but received
an extremely structured residuals pattern indicating the model was flawed.
I then tried clmm2 (package "ordinal") and MCMCglmm (package "MCMCglmm")
which should work with ordinal variables. Both seem to be "over
optimistic" and find significant results where I don't expect them to be
(essentially in all predictors). The latter's under-conservatism with my
data is also pronounced by the fact that it found significant or close
to significant results in a completely random variable I generated and
included in the model.
Does anyone have an advise or some good experience with mixed models of
an ordinal response?
Best,
Omer
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