[R] Error in MuMIn "models are not all fitted to the same data"

, data=survey.full, REML=F) MExAvg=model.avg(rank=AIC, MEx24, MEx7, MEx10, MEx47, MEx29, MEx22) Error in model.avg.default(rank = AIC, MEx24, MEx7, MEx10, MEx47, MEx29, : models are not all fitted to the same data Lilly Dethier [[alternative HTML version deleted]] _

[R] Interpreting Rasch models

I'm testing an education assessment (evaluating quantitative skills in biology students) for reliability. I used cronbach's alpha, but got a really low alpha which I think is likely due to my small number of questions (12) and the fact that the questions are of varying difficulty. After a lot of re