# Comparison of real and simulated moments

Hi.

I solved and simulated an RBC model in non-linear form.Now,I want to compare simulated and real data moments( standard deviation).
My question is that I solved and simulated the model in a non-linear form but not log-linear.

When I want to compare the simulated moments with real data moments, can I use logarithm of GDP and logarithm of Consumption?

I seasonally adjusted my real data, then I transformed them to Logarithm for example LogGDP or LogCONSUMPTION, then I derived cycle with HP filter and then I compared the standard deviation of these variables with standard deviation of simulated data in Dynare.

I want to know that my work is right or not?

I ask this question,because my model is not Log-Linear,but when I compare the standard deviations of simulated and real data, I use logarithm of real data such as GDP,Consumption,Investment

Thank you so much.

You need to compare log-data with the same filter. See e.g. https://github.com/JohannesPfeifer/DSGE_mod/blob/master/RBC_baseline/RBC_baseline.mod

Thank you much.I saw your RBC codes but you adjusted your model in Dynare to be solved in log-linear form, and not in linear form.I have written the model only in non-linear form in Dynare and Dynare solve it in linear form not Log-Linear form. According to the aforementioned point my work is right or not?

I did not transformed the model to log-linear form because we have not strictly positive steady state values in the model.

No, I did not do log-linearize. The model is completely nonlinear. I simply appended the logged variables of interest.

Thank you so much professor.

Hi
When we add for example log(y) to the non linear code should we compare the theoretical moments of this variable with empirical moments computed based on log (y)-hp filter(logy) ? is it correct?
Thanks

That always depends what you are trying to do. But usually, you compare filtered data moments to model data filtered in exactly the same way.