I have just discovered the newly updated priorsense (version 1.0.1) package.

I have done a gaussian family meta analysis using brms with the cmdstanr backend.

I want to assess the sensitivity of the model to variations in the power scaled prior and likelihood.

The model runs successfully with Rhat = 1.00 and Bulk and Tail ESS > 10000.

The loo function with moment_match = TRUE returns

```
Estimate SE
elpd_loo -5.2 2.5
p_loo 14.6 1.9
looic 10.3 5.1
------
MCSE of elpd_loo is 0.1.
MCSE and ESS estimates assume MCMC draws (r_eff in [0.5, 0.7]).
All Pareto k estimates are good (k < 0.7).
```

The call to priorsense package function returns:

```
powerscale_sensitivity(lipo.smd.ls.brms.0, variable = c('mu', 'sigma'))
Error in UseMethod("log_prior_draws") :
no applicable method for 'log_prior_draws' applied to an object of class "brmsfit"
```

This appears to be the correct call to the priorsense function.

The model code is as follows. I needed to adjust the step_size and adapt_delta.

```
priors <- c(prior(normal(0, 1), class = Intercept),
prior(normal(0, 0.5), class = sd))
formula0 <- bf(formula = yi|se(vi) ~ 1 + (1|slab),
family = gaussian())
lipo.smd.ls.brms.0 <- brm(formula = formula0,
data = tmp.smd.ls.df,
prior = priors,
seed = 12345,
sample_prior = TRUE,
save_pars = save_pars(all = TRUE),
save_cmdstan_config = TRUE,
control = list(adapt_delta = 0.9,
step_size = 0.005),
iter = 32000,
chains = 4,
cores = 4)
```

Here is the data. There are 13 studies included in the meta analysis. The data uses the standardized mean difference of means with yi and vi calculated in the metafor package.

```
slab yi vi
1 Chevrollier 2022 -0.1567 0.0528
2 Colvin 2018 0.1614 0.0749
3 Curtis 2018 -0.8635 0.4914
4 Fafaj 2020 0.3031 0.0361
5 Fidkowski 2021 -0.2320 0.0596
6 Ha 2019 -0.0519 0.0909
7 Herskovic 2018 -2.1493 1.4966
8 Hutchins 2015 -0.7036 0.0745
9 Hutchins 2016 -0.3617 0.0689
10 Nedelijkovic 2020 -0.3414 0.0299
11 Perdikis 2022 -0.5946 0.0696
12 Truong 2021 -0.4042 0.0404
13 Yeap 2022 0.2106 0.0516
```

Please also provide the following information in addition to your question:

- Operating System: Mac OS 14.5
- brms * Version: 2.21.0

*priorsense*Version: 1.0.1