Hi all,

I’m having some trouble getting the Mr part of a MrP model to fit efficiently with brms. I’m hoping someone may be able to help guide me toward a better fit.

Here is the R code for the model:

```
vote_model <- brm(mvbind(vote_trump,vote_clinton) ~ 1 +
# pop level
state_clinton + state_black_pct + state_hispanic_pct + state_white_protestant +
# group effects
(1|sex) + (1|race) + (1|age) + (1|edu) + (1|state_name) + (1|region) +
# interactions b/t group effects
(1|race:edu) + (1|age:edu) + (1|race:region),
data = cces,
family = bernoulli(link = "logit"),
# stan stuff
iter=1000, chains=1, cores=1, warmup=500,
algorithm='sampling',
save_model = 'output/stan_model_code.stan',
# priors (https://github.com/stan-dev/stan/wiki/Prior-Choice-Recommendations)
prior = c(set_prior("normal(0, 1)", class = "Intercept"),
set_prior("student_t(3, 0, 4)", class = "sd",resp=c('votetrump','voteclinton'))),
# help sampling algorithm converge (http://mc-stan.org/misc/warnings.html)
control = list(adapt_delta = 0.95,
max_treedepth = 10),
seed = 20190605,
refresh = 1)
```

I let it run for about 12 hours and then gave up, after which it had only completed 200 iterations. The dataset is just 40k survey respondents, so that doesn’t seem right.

Help?

Elliott

Session info:

```
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