I was looking at the `example_model`

in rstanarm and a bit unclear about some of the output.

```
library(rstanarm)
example(example_model)
tail(example_model$stan_summary[, 1:2])
```

which gives the following output

```
#> mean se_mean
#> b[(Intercept) herd:14] 1.02671072 0.016200257
#> b[(Intercept) herd:15] -0.62123581 0.019984998
#> b[(Intercept) herd:_NEW_herd] 0.00726711 0.020258006
#> Sigma[herd:(Intercept),(Intercept)] 0.65040705 0.021683219
#> mean_PPD 1.77508929 0.006152789
#> log-posterior -114.76141580 0.268875928
```

Is `b[(Intercept) herd:_NEW_herd] `

here the mean that each group level intercept is drawn from? Or is it a posterior predictive distribution for a new hypothetical group?

I couldn’t find this documented, but would appreciate a reference!