# How to add prior for variance of regression coefficients

**URL:** <https://discourse.mc-stan.org/t/how-to-add-prior-for-variance-of-regression-coefficients/26282>\
**Category:** brms\
**Created:** [February 10, 2022, 4:40pm UTC](https://discourse.mc-stan.org/t/how-to-add-prior-for-variance-of-regression-coefficients/26282 "2022-02-10T16:40:24Z")\
**Posts on this page:** 1\
**Page:** 1

<div class="post-metadata">

**Author:** ![GhostMaster](https://avatars.discourse-cdn.com/v4/letter/g/a183cd/32.png) [@GhostMaster](https://discourse.mc-stan.org/u/GhostMaster)\
**Post date:** [February 10, 2022, 4:40pm UTC](https://discourse.mc-stan.org/t/how-to-add-prior-for-variance-of-regression-coefficients/26282/1 "2022-02-10T16:40:24Z")

</div>

I am using brms package and I want to add another stage to coefficient priors. What I mean by that is, let’s say our regression coefficients are normally distributed with mean 0 and variance tau. I want to assign a prior for tau as in the below picture.

 ![Model](https://canada1.discourse-cdn.com/flex030/uploads/mc_stan/original/2X/1/154f9736b08616ee1395333759c976cebe000c46.png)