I have some data I would like to model which involves choice of food by
dung beetles.
There are a number of experiments where in each case, there are five
choices. Overall there are more than 5 different foods being compared
(including a placebo) and different experiments use different comparisons.
The problem is a generalization of Bradley-Terry but it differs from
some generalizations in that the comparisons are not pairwise, and they
don't produce a full ordering, just that one is preferred to the other
four possibilities.
I have had a look at the BradleyTerry2, eba, pmr and MLCM packages, none
of which appear to provide the required functionality. I have also
looked at a number of papers (Hunter, 2004; Firth, 2005; Huang Weng and
Lin, 2006; and Fujimoto, Hino and Murata 2011). I think fitting using
maximum likelihood should be possible, but would welcome any pointers to
useful code, relevant ideas, or similar analyses.
David Scott
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