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Greetings- a reviewer for a paper of mine noted an anomaly in some models I ran using glmmPQL (from the MASS package). Specifically, the models are three-level hierarchical probit models estimated using PQL under R. The anomaly is that the log-likelihoods decrease (or, alternatively -2logLik increases) as variables are added to the null model. This is unusual, and I'm trying to figure out how to interpret it. I've found some indication (e.g., at http://www.ssicentral.com/hlm/hlm00150.htm) that PQL estimation doesn't produce meaningful log-likelihoods, but I'm suspiciou...