fit <- glm(cbind(success, failure) ~ c + b + nb -1,
family=binomial, data=dat)
which works fine. I can also include the age factor, which
also seems to work ok:
fit2 <- glm(cbind(success, failure) ~ c + b + nb +
as.factor(age) -1, family=binomial, data=dat)
Now, since each rater performs ratings on each of the 3
treatment combinations, I was interested in including rater
as a random factor. My naive method was to use glmmPQL from
library MASS:
fit3 <- glmmPQL(cbind(success, failure) ~ c + b + nb -1,
random = ~1|rater, family=binomial, data=dat)
However, I get the following error:
iteration 1
Error in MEEM(object, conLin, control$niterEM) :
Singularity in backsolve at level 0, block 1