# If x is exogenous and not shocked in the Policy run, why does it have a nonzero value in the results?

Here we are considering a dynamic model solved via RunDynam/RunMONASH etc. Suppose that the variable x is exogenous in the Policy run and is not shocked in the Policy shocks. How can x have a nonzero value in the Policy run?

If x is also exogenous and not shocked in the Base run, the Policy result for x will be zero, as you expect.

But if x is endogenous in the Base run, the Policy result for x will be the same as the endogenous result from the Base, as we explain below.

Any period (year) in the Policy run must duplicate the corresponding period in the Base, with the addition of any Policy shocks in that period. In order to duplicate the Base, the values given to all exogenous variables in the Policy are those from the same period in the Base, even if that variable was endogenous in the Base.

Example. If variable x is endogenous in year 2006 of the Base and its value is 3.2% in that year of the Base, and if x is exogenous and not shocked in year 2006 of the Policy, its value will be 3.2% in year 2006 of the Policy. That is the value you will see in year 2006 if you look at the year-on-year results for the Policy.

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