Hello Stan users:

I am trying to fit the following MELS model using the brms package in R:

mod_mels ← brm(bf(y ~ x + (1 | id),

sigma ~ x + (1 | id)),

prior = set_prior(“normal(0,5)”),

data = df)

I would like to specify a correlation between the mean function and the level 1 variance function. I don’t think there is a default for correlation between these two parameters in brms. How do I specify this correlation? Many thanks!