[R-sig-ME] Cross-classified multiple membership models

[Roberts, Kyle]

Dear All,

Is it possible to perform a cross-classified multiple membership model with lmer? Here's the data scenario. I have mathematics data for 2500 kids across four measurement occasions. At each occasion, they are in a separate teacher's classroom (cross-classified, not truly nested). However, there are times that the kids are taking more than one math course during that semester (multiple membership; for example, in a remedial math course AND in another math course with their cohort). Here's an example:

id      time        teacher     score
1       1           1005        118
1       2           1021        125
1       2           1024        125
1       3           1151        139
1       4           1148        164

See how at time==2, person 1 is in two separate math courses, but receives the same score for both "rows" of data since the administration of the instrument occurred only once at that time point.

When I looked through the archive, I found one reference from Doug a year ago that said that he didn't think this was possible yet. However, I thought that maybe someone worked a solution since then.

http://finzi.psych.upenn.edu/R-sig-mixed-models/2009q1/002080.html

Thanks,
Kyle