Background: Relative risk is a summary metric that is commonly used in
epidemiological investigations. Increasingly, epidemiologists are using log-binomial
models to study the impact of a set of predictor variables on a single binary
outcome, as they naturally offer relative risks. However, standard statistical
software may report failed ... read moreconvergence when attempting to fit log-binomial models in
certain settings. The methods that have been proposed in the literature for dealing
with failed convergence use approximate solutions to avoid the issue. This research
looks directly at the log-likelihood function for the simplest log-binomial model
where failed convergence has been observed, a model with a single linear predictor
with three levels. The possible causes of failed convergence are explored and
potential solutions are presented for some cases.
Keywords: Log-binomial, Non-convergence, Failed convergence, Relative
risk, Method of maximum likelihood, Log relative risk, Likelihood estimation, Maximum
likelihood estimates, Logistic regression alternatives.