# How to introduce a variable in steady state in an equation?

**URL:** <https://forum.dynare.org/t/how-to-introduce-a-variable-in-steady-state-in-an-equation/3641>\
**Category:** Dynare help (legacy posts)\
**Created:** [23 January 2014 18:04 UTC](https://forum.dynare.org/t/how-to-introduce-a-variable-in-steady-state-in-an-equation/3641 "2014-01-23T18:04:24Z")\
**Posts on this page:** 4\
**Page:** 1

<div class="post-metadata">

**Author:** ![Raulfz](https://forum.dynare.org/letter_avatar_proxy/v4/letter/r/f17d59/32.png) [@Raulfz](https://forum.dynare.org/u/Raulfz)\
**Post date:** [23 January 2014 18:04 UTC](https://forum.dynare.org/t/how-to-introduce-a-variable-in-steady-state-in-an-equation/3641/1 "2014-01-23T18:04:24Z")

</div>

I want to write the following equations in dynare but I don´t know how.

Psi=Piss/Pi where Piss is the inflation rate in steady state and pi is the inflation rate. Obiously Psi in steady state should be 1. Note I don´t want to use Piss as a parameter, because if I change the parameters model I should get another steady state inflation.

As another example, how should I introduce the following process:

Log(R(t) / R)= taupi \* log(pi(t)/pi) + tauy \* log(y(t)/y)+ epsilonr(t)

where the variables without (t) are the variables in steady state. For example pi is pi(t) in steady state.

Thank you so much.

---

<div class="post-metadata">

**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:** [23 January 2014 18:41 UTC](https://forum.dynare.org/t/how-to-introduce-a-variable-in-steady-state-in-an-equation/3641/2 "2014-01-23T18:41:07Z")

</div>

You could use the steady\_state-operator. See my “A Guide to Specifying Observation Equations for the Estimation of DSGE Models” at [sites.google.com/site/pfeiferecon/Pfeifer\_2013\_Observation\_Equations.pdf](https://sites.google.com/site/pfeiferecon/Pfeifer_2013_Observation_Equations.pdf) for an example on how to do this.

---

<div class="post-metadata">

**Author:** ![Raulfz](https://forum.dynare.org/letter_avatar_proxy/v4/letter/r/f17d59/32.png) [@Raulfz](https://forum.dynare.org/u/Raulfz)\
**Post date:** [23 January 2014 23:43 UTC](https://forum.dynare.org/t/how-to-introduce-a-variable-in-steady-state-in-an-equation/3641/3 "2014-01-23T23:43:37Z")

</div>

Thank you very much. I am going to read your paper.

---

<div class="post-metadata">

**Author:** ![tom\_mercer](https://forum.dynare.org/letter_avatar_proxy/v4/letter/t/7feea3/32.png) [@tom\_mercer](https://forum.dynare.org/u/tom_mercer)\
**Post date:** [25 January 2014 21:06 UTC](https://forum.dynare.org/t/how-to-introduce-a-variable-in-steady-state-in-an-equation/3641/4 "2014-01-25T21:06:56Z")

</div>

Me too! Interesting