I only have a small doubt, I am calibrating my model by the method of moments, adjusting certain parameters to the great ratios, these are: internal-public-debt-to-GDP, external-public-debt-to-GDP, consumption-to -GDP, Trade-balance-to-GDP, Government-Investment-to-GDP, etc.
When calculating these proportions from the data in quarterly frequency, (after adjusting for seasonality), I find that their behavior is not stationary, in many cases there appear to be trends. My questions are:
Is it still valid to take the average of these series as steady-state values?
I was thinking that since they are steady-state values it is better to obtain the trend component of each of the variables and divide it by the trend component of GDP, (using one-sided HP filter). Could this be a better option?
Thanks in advance.