I have 2 study sites containing data from a species of wildlife. I am trying to evaluate resource selection use a use vs. availability analysis where used animal locations = 1 and random locations = 0. I used the following R code to address my question of interest:
results <- glmer(R0A1 ~ MP_Scaled * Season1 + MPHW_Scaled * Season1 + HW_Scaled * Season1 + YP_Scaled * Season1 + AG_Scaled * Season1 + Shrub_Scaled * Season1 + (1|ID) + (1|Site), data = turkey2nd, family = binomial, glmerControl(optimizer = "bobyqa", optCtrl = list(maxfun = 100000))) summary(results)
I accounted for variation in unequal sample sizes for animals (i.e., number of telemetry locations/individual) by using
(1|ID) but I also wanted to account for variability in habitat selection across study sites using
(1|Site). I've always heard that you can specify study site as a random effect (and is typically encouraged by reviewers); however, I recently heard that I should include study site as a fixed effect to get the same inference as
(1|ID) (i.e., adjusting for the effect of unequal sample sizes among sites on the marginal fixed effect estimate). The concern is that I have 73 individuals for
(1|ID) but only 2 sites for
(1|Site). What are some thoughts on this?