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IRFs to inactive shocks

PostPosted: Wed Jul 16, 2014 1:31 am
by reubenpjacob
Hi All
I have been estimating a DSGE model using only a subset of the shocks, setting some shock st. deviations to zero. I noted that dynare produces impulse responses for even the inactive shocks! It must be noted that in the 'inactive-shock triggered' IRFs the deviations of the endogenous variables from steady-state are very very small, to the order of 10^-10. Have any of you experienced the same? And if so, what could be the explanation?
Thanks
Reuben

Re: IRFs to inactive shocks

PostPosted: Wed Jul 16, 2014 8:46 am
by jpfeifer
To prevent dealing with non-positive definite covariance matrices, Dynare adds a small number to the diagonal of the covariance matrix:
Code: Select all
    SS(M_.exo_names_orig_ord,M_.exo_names_orig_ord)=M_.Sigma_e+1e-14*eye(M_.exo_nbr);

In most cases, no IRFs are displayed as IRFs are only printed for cases where the response exceeds
Code: Select all
options_.impulse_responses.plot_threshold=1e-10;

In your case, the IRFs seem to barely exceed this threshold, resulting in displayed graphs. But this is nothing to worry about.

Re: IRFs to inactive shocks

PostPosted: Thu Jul 17, 2014 11:47 pm
by reubenpjacob
Thanks, Johannes! I must thank you for your work on this website. It is fantastic.