Stan model

model2<- stan_glmer(
  ADG~ADF + Included2017 + (1|Studycode),
  data = d, family = gaussian,
  prior_intercept = normal(100,3, autoscale = TRUE),
  prior = normal(0, 2.5, autoscale = TRUE), 
  prior_aux = normal(9, 3, autoscale = TRUE),
  prior_covariance = decov(reg = 1, conc = 1, shape = 1, scale = 1),
  chains = 4, iter = 5000*2, seed = 84735)
summary(model2)

tidy_summary_1 <- tidy(model2, effects = "fixed",conf.int = TRUE, conf.level = 0.80)
tidy_summary_1 <- tidy(model2, effects = "ran_vals",conf.int = TRUE, conf.level = 0.80)

plot(model2)
mcmc_areas(model2, pars = vars(starts_with("b")), prob = 0.8) + 
  geom_vline(xintercept = 0)