Let's consider an exogenous oil price shock ($e_t$) as an example in the following equation $oil_t = \rho \; oil_{t-1} + e_t$, where $oil_t$ is one variable in a VAR system. We normally want to recover $e_t$ based on some structural model we have for some given economy. So I guess that makes $e_t$ also country-specific, right?
So, for example, we cannot just look visually at oil-price time series data and say that oil price shocks are more volatile or less volatile. Like it depends on the economy of interest?
So although oil prices may be more or less volatile in general for a given period, it does not say anything about oil price shocks for a given economy, I guess. We need a structural model to recover the oil-price shocks to see how it behaves, right?