Hi,

I’m fitted two hierarchical distance decay models, one with a linear decay and another with an exponential decay.

Linear decay

```
similarity ~ normal(mu, sigma)
mu[i] =a[basin_id[i]] + b[basin_id[i]] * distance[i]
```

Exponential decay

```
similarity ~ normal(mu, sigma)
mu[i] =a[basin_id[i]]) * exp(b[basin_id[i]] * distance[i]
```

Posterior predictive checks seem to be ok for both models (please correct me If I’m wrong).

**Linear model**

**Exponential model**

I would like to formally compare both models and determine which one fits the data best. I read:

http://mc-stan.org/loo/articles/loo2-with-rstan.html

and was thinking if I can/should compare both models with ELPD as shown in the above vignette.

Thanks

Filipe