Hi all,

I’d like to estimate the effect of two predictors, `pred1`

and `pred2`

on mean and sigma of a normal distribution. In addition, I’d like to model:

a) the correlations between random-effect intercept and slopes (and between slopes), only for the mean

b) the correlation between random intercept for mean with random intercept for sigma

c) **uncorrelated** random intercept for sigma with random slopes for mean

That is, I’d like the formula to be something like this, which does not work because of the double specification of `(1|subject)`

:

```
bf(response ~ (1|SID|subject) + (1+pred1+pred2|subject) + pred1 + pred2,
sigma ~ (1|SID|subject) + pred1 + pred2)
```

And not this, because it doesn’t fulfil c) above:

```
bf(response ~ (1+pred1+pred2|SID|subject) + pred1 + pred2,
sigma ~ (1|SID|subject) + pred1 + pred2)
```

Is this possible with brms?

Thank you!

João

- Operating System: Linux 5.3.0 (Ubuntu 18.04.1)
- brms Version: 2.12.0