[R-sig-ME] Error fitting reduced model in bglmer for LRT

[Josie Galbraith]

Hi all,

In following on from this post
<https://stat.ethz.ch/pipermail/r-sig-mixed-models/2015q1/023191.html>,
regarding using blme and fixed effect priors to address issues of complete
separation in my data, I've come up against a problem trying to fit reduced
models for testing the model terms using likelihood ratio tests (LRT).

Firstly, can I use LRTs (anova()) for testing the fixed effects of bglmer
models, as I would for glmer models?

If yes, then I need help understanding why I'm getting the following error
fitting a reduced bglmer model:
"Error in if (nrow(cov) == 2) { : argument is of length zero"

This is my full model:
SE.les.mod = bglmer (LESION ~ FOOD*SEASON +(1|SITE), data = SEYE.df, family
= binomial, fixef.prior = t(1,2.5), cov.prior = NULL)

I can fit a model without the interaction term ok:
SE.les.add = bglmer (LESION ~ FOOD+SEASON +(1|SITE), data = SEYE.df, family
= binomial, fixef.prior = t(1,2.5), cov.prior = NULL)

But I get the error message with both of the single fixed effects models:
SE.les.FOOD = bglmer (LESION ~ SEASON +(1|SITE), data = SEYE.df, family =
binomial, fixef.prior = t(1,2.5), cov.prior = NULL)
SE.les.SEAS = bglmer (LESION ~ FOOD +(1|SITE), data = SEYE.df, family =
binomial, fixef.prior = t(1,2.5), cov.prior = NULL)

Thanks very much,
Josie



-- 
*Josie Galbraith* MSc (hons)

PhD candidate
*University of Auckland *
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