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Gamma Mixed Model, Posthoc Odds Ratio

Posted: Mon Mar 25, 2024 9:48 pm
by bencturnbull
Hi Friends,

When I run a generalized linear mixed model, with a gamma distribution and log link, I get no exp(B) values for the posthocs. I do, however, get them for the fixed effects parameters. I also get them if running a negative binomial distribution.

Is there a solution?
Is there just no way to estimate the effects size of posthocs from a gamma distribution?

Thanks

Re: Gamma Mixed Model, Posthoc Odds Ratio

Posted: Tue Mar 26, 2024 11:15 am
by mcfanda@gmail.com
Hi

GAMLj3 implements posthoc tests for beta models (following R emmeans package) testing differences in probabilities (o proportions). So, the posthoc values are basically marginal effects for categorical independent factors. As such, the exp(b) would not make much sense. However, you can always get the effect size of the comparison from the "Parameter Estimates" and use the adjusted z-tests and p-values from the post-hoc table.