# Simult\_ attempt

**URL:** <https://forum.dynare.org/t/simult-attempt/17265>\
**Category:** Stochastic simulations\
**Created:** [9 January 2021 21:05 UTC](https://forum.dynare.org/t/simult-attempt/17265 "2021-01-09T21:05:48Z")\
**Posts on this page:** 1\
**Showing post:** 7

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**Author:** ![jpfeifer](https://forum.dynare.org/user_avatar/forum.dynare.org/jpfeifer/32/5044_2.png) [@jpfeifer](https://forum.dynare.org/u/jpfeifer)\
**Post date:** [13 January 2021 10:40 UTC](https://forum.dynare.org/t/simult-attempt/17265/7 "2021-01-13T10:40:32Z")

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A counterfactual needs to be conducted for one set of parameters. The underlying issue is Jensen’s Inequality. The same happens for IRFs. See

> [@Irfs after estimation of a DSGE model](https://forum.dynare.org/t/irfs-after-estimation-of-a-dsge-model/17031/4):
>
> It’s about Jensen’s Inequality. Denote the IRF at parameter \theta\_i with IRF(\theta\_i) with N being the number of MCMC draws. Then \frac{1}{N}\sum\_{i=1}^N IRF(\theta\_i)\neq IRF(\frac{1}{N}\sum\_{i=1}^N \theta\_i) The first object is the mean IRF generated by estimation, while the second object is the IRF at the parameter mean generated by stoch\_simul`.

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