# Ordinal-ish model: setting priors and pp\_check

**URL:** <https://discourse.mc-stan.org/t/ordinal-ish-model-setting-priors-and-pp-check/24591>\
**Category:** brms\
**Tags:** specification\
**Created:** [September 27, 2021, 8:04pm UTC](https://discourse.mc-stan.org/t/ordinal-ish-model-setting-priors-and-pp-check/24591 "2021-09-27T20:04:34Z")\
**Posts on this page:** 1\
**Showing post:** 7

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**Author:** ![aisa2](https://avatars.discourse-cdn.com/v4/letter/a/d78d45/32.png) [@aisa2](https://discourse.mc-stan.org/u/aisa2)\
**Post date:** [October 7, 2021, 7:24pm UTC](https://discourse.mc-stan.org/t/ordinal-ish-model-setting-priors-and-pp-check/24591/7 "2021-10-07T19:24:27Z")

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That sounds interesting, though I’m not sure I have the custom likelihood chops for that either ;)

A related question I had was how to set the priors for these ordinal-type variables.

I understand that the output has multiple intercepts corresponding to the thresholds. I tried priors for “Intercept” generally at Normal(0,1) and Normal(0,5) – I guess this is in the logit scale as for other brms models.

However, this means that the left- and right-most intercepts would be pretty far away from this prior, right? Should I specify a different prior for each intercept, as I’ve seen [here](https://discourse.mc-stan.org/t/specifying-priors-for-ordinal-adjacent-category-model/14990/14)?

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