[R-meta] Meta-regression or simple GLMM

[Denis Lafage]

Hello all,


I am conducting my first meta-analysis on the diet of arthropod predators (expressed as a proportion of aquatic prey) in riparian ecosystems. Given the heterogeneity of technics to estimate this proportion, I recomputed all the estimates from raw data extracted from figures and tables. Now I have a dataset with a proportion of aquatic prey and a standard deviation (given by the Bayesian mixing model used to calculate the proportion) for each species, on each sampling site of each study.

I want to see if local and landscape factors (data I produced from satellite data) explain the proportion of aquatic prey in the diet. For each random variable, I have one value per sampling site.


As it is almost a primary dataset, I started with a simple GLMM on mean proportion of aquatic prey with study and site as fixed factors and local and landscape variables as random factors.

But maybe I'd rather go for a meta-regression with rma.glmm?

- In this case, how do you deal with a proportion (which is not the result of failure/success) as effect size? Should I use measure="PLO" for logit transformed proportions (i.e., log odds) ?

- Should I use the standard error of the proportion of aquatic preys for each site or calculate the standard error from the standard deviations I obtained from the Bayesian mixing model?


Thank you for your help


Best regards


Denis


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