lmer - error message
I think my problem is that I can't
incorporate the 'lake' variable in a fixed-effect interaction because it is only has one binary observation. ?But I don't know what to do to be able to fit this model. ?Any help would be greatly appreciated! -Sean
?In principle you should be able to fit this model, but the error message is telling you that there are numeric problems -- it may just be that your data are a little too sparse in some direction.
Yes. Consider the collinearity between Age and Year, i.e. for a given cohort (mos or all captured by "fishID" ?) they are essentially the same variable with different units. So I would suspect the problem is you are over fitting those. A few suggestions:
?* try centering Age, or re-introducing the intercept, to see if you can get something to work. ?* You _might_ try the development version of lme4 (lme4Eigen, on r-forge) ?* plot your data to see if you see anything odd about the data ?* perhaps try making Year a fixed effect -- 4 levels is fairly small for a random effect ?* Ask further questions on the r-sig-mixed-models mailing list. ?Ben Bolker
Add one more to those: make sure your random effects are indeed crossed. If they are nested (without knowing anything about your data, just given their names that's a possibility), you could try nlme::lme. Elai
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