Calculate historical borrowing metrics using summary output from a fitted borrowing model and analogous summaries from the benchmark models.

`hb_metrics(borrow, pool, independent)`

- borrow
A data frame returned by

`hb_summary()`

for a borrowing model, either the hierarchical model or the mixture model.- pool
A data frame returned by

`hb_summary()`

for the pooled model.- independent
A data frame returned by

`hb_summary()`

for the independent model.

A data frame with borrowing metrics.

Other summary:
`hb_summary()`

```
if (!identical(Sys.getenv("HB_TEST", unset = ""), "")) {
data <- hb_sim_independent(n_continuous = 2)$data
mcmc_borrow <- hb_mcmc_hierarchical(
data,
n_chains = 1,
n_adapt = 100,
n_warmup = 100,
n_iterations = 200
)
mcmc_pool <- hb_mcmc_pool(
data,
n_chains = 1,
n_adapt = 100,
n_warmup = 50,
n_iterations = 50
)
mcmc_independent <- hb_mcmc_independent(
data,
n_chains = 1,
n_adapt = 100,
n_warmup = 50,
n_iterations = 50
)
borrow <- hb_summary(mcmc_borrow, data)
pool <- hb_summary(mcmc_pool, data)
independent <- hb_summary(mcmc_independent, data)
hb_metrics(
borrow = borrow,
pool = pool,
independent = independent
)
}
```