Optimize Stan code - hierarchical model

[emiruz]

So in this thread @avehtari gives OP the following advise:

@avehtari

You have not set any prior on coefs, which means the prior is improper and combined with bernoulli_logit the posterior can be improper and MCMC can’t produce valid posterior draws even in infinite time. Add proper priors and report the result here

if you’re looking to reparameterise because the model runs slow or doesn’t converge then @avehtari advise RE priors might apply here too since none of the parameters seem to have priors in your model unless I’ve misunderstood something.