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

- Operating System: Mac OS
- brms Version: 2.10.0

Hello, I’m looking to build a relatively simple model where I can manually control a scaling factor on the observation variance.

I have a number of independent observations y1, …, yn. Each observation comes from a normal distribution with a variance of sigma_sqrd / n_i, where n_i is a known value for each observation and I want to estimate sigma as a parameter. I then want to regress these y values on a set of fixed and random effects. How do I set up a model with a variance structure like this?

Thanks,

Eric.