# Question about theoretical moment after implementing ramsey\_policy

**URL:** <https://forum.dynare.org/t/question-about-theoretical-moment-after-implementing-ramsey-policy/10681>\
**Category:** Optimal Policy\
**Created:** [2 September 2017 20:02 UTC](https://forum.dynare.org/t/question-about-theoretical-moment-after-implementing-ramsey-policy/10681 "2017-09-02T20:02:10Z")\
**Posts on this page:** 1\
**Showing post:** 4

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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:** [3 September 2017 14:45 UTC](https://forum.dynare.org/t/question-about-theoretical-moment-after-implementing-ramsey-policy/10681/4 "2017-09-03T14:45:52Z")

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1. No. As I said

> [@What are "theoretical moments" referring to?](https://forum.dynare.org/t/what-are-theoretical-moments-referring-to/4735/3):
>
> At order=1, the solution to your model has a the form of a linear state-space model. This can be used to analytically compute the endogenous moments. See e.g. Hamilton (1994): Time Series Analysis. This is what Dynare does when you request theoretical moments (periods=0). In case of order=2, Dynare provides a second-order accurate approximation to the true second moments based on the linear terms of the second-order solution (see Kim, Kim, Schaumburg and Sims (2008)).  
> If you specify `periods>0` Dynare will instead simulate data series based on the perturbation solution to your model and compute the moments of these simulated series.

1. I ran your code. The unit roots seem strange.

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