# Negative exogenous shocks in a stochastic context

**URL:** <https://forum.dynare.org/t/negative-exogenous-shocks-in-a-stochastic-context/254>\
**Category:** Dynare help (legacy posts)\
**Created:** [27 February 2007 01:47 UTC](https://forum.dynare.org/t/negative-exogenous-shocks-in-a-stochastic-context/254 "2007-02-27T01:47:45Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![homer05](https://forum.dynare.org/letter_avatar_proxy/v4/letter/h/57b2e6/32.png) [@homer05](https://forum.dynare.org/u/homer05)\
**Post date:** [27 February 2007 01:47 UTC](https://forum.dynare.org/t/negative-exogenous-shocks-in-a-stochastic-context/254/1 "2007-02-27T01:47:45Z")

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Hi,

Is there anyway to stipulate that in a stochastic model the exogenous shock is negative. e.g. instead of producing impulse response graphs for a positive shock it produces one for a negative shock?

Many thanks and my apologies if this question turns out to have an obvious and already explained answer.

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**Author:** ![MichelJuillard](https://forum.dynare.org/user_avatar/forum.dynare.org/micheljuillard/32/5318_2.png) [@MichelJuillard](https://forum.dynare.org/u/MichelJuillard)\
**Post date:** [27 February 2007 09:19 UTC](https://forum.dynare.org/t/negative-exogenous-shocks-in-a-stochastic-context/254/2 "2007-02-27T09:19:28Z")

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There is no option to do that in Dynare, but if you change the sign of the shock in the model, a positive impulse to the modified shock will give you the response to a negative impulse to the original shock.

Best

Michel

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**Author:** ![homer05](https://forum.dynare.org/letter_avatar_proxy/v4/letter/h/57b2e6/32.png) [@homer05](https://forum.dynare.org/u/homer05)\
**Post date:** [27 February 2007 21:07 UTC](https://forum.dynare.org/t/negative-exogenous-shocks-in-a-stochastic-context/254/3 "2007-02-27T21:07:53Z")

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Woops. I should’ve thought of that previously. Thanks a lot Michel!