Zero variance and Std. Dev. using lmer?
On Tue, 13 Jan 2009, Luciano La Sala wrote:
Dear R-people: I have run a GLMM (using lmer) with the fixed and random effects detailed below. Oddly I think, I get zero variance and Std. Dev. values. How is that possible? Does it mean that the RE "NestID" is not helping to account for autocorrelation among sibling chicks at the nest level? Or is this a small sample size problem? model <- lmer(Death10~HO+ClutchSize+SibComp+Yr+(1|NestID),family=binomial,1)
Either, I would think. Have you performed a simple test for extrabinomial variation? eg Tarone test or Chi-square [latter is just contingency Chi-square test for NestID x Death10] David Duffy.
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