[R-sig-ME] Rasch with lme4

[Daniel Ezra Johnson]

In the output for this model:

>> M2 = lm(Reaction ~ Days + Sex + factor(Subject), sleepstudy)
>> summary(M2)
>

You will see that one of the coefficients is NA. If you put
factor(Subject) before Sex it would be SexMale that comes out NA.

Nested fixed effects will always return an error (or incomplete
model), unless I'm completely mistaken.

Dan