# Pareto K diagnostics and kfold model comparison

**URL:** <https://discourse.mc-stan.org/t/pareto-k-diagnostics-and-kfold-model-comparison/7409>\
**Category:** brms\
**Tags:** loo\
**Created:** [January 23, 2019, 8:16pm UTC](https://discourse.mc-stan.org/t/pareto-k-diagnostics-and-kfold-model-comparison/7409 "2019-01-23T20:16:49Z")\
**Posts on this page:** 1\
**Showing post:** 11

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**Author:** ![sbashevkin](https://yyz2.discourse-cdn.com/flex030/user_avatar/discourse.mc-stan.org/sbashevkin/32/3963_2.png) [@sbashevkin](https://discourse.mc-stan.org/u/sbashevkin)\
**Post date:** [January 29, 2019, 6:09pm UTC](https://discourse.mc-stan.org/t/pareto-k-diagnostics-and-kfold-model-comparison/7409/11 "2019-01-29T18:09:50Z")

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> [@paul.buerkner](#):
>
> @sbashevkin Please use the “Interfaces - brms” tag for brms related questions. Otherwise, I will likely overlook it (I changed the tag manually this time).

Sorry about that. I thought this question would be a more general one about interpretation of loo diagnostics.

> [@paul.buerkner](#):
>
> With regard to the number of parameters, `parnames()` won’t help you. To what kind of number of parameters are you referring to? Effective number of parameters?

I am interested in the number of parameters that I should be comparing to the p\_loo estimates, as @avehtari refers to here: [A quick note what I infer from p\_loo and Pareto k values - #3 by avehtari](https://discourse.mc-stan.org/t/a-quick-note-what-i-infer-from-p-loo-and-pareto-k-values/3446/3) where he says

> [@A quick note what I infer from p\_loo and Pareto k values](https://discourse.mc-stan.org/t/a-quick-note-what-i-infer-from-p-loo-and-pareto-k-values/3446/3):
>
> start by counting all parameters in the parameters block, and then refine if necessary.

I was thinking that the results of `parnames()` would be equivalent to the number of parameters in the Stan parameters block?

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