I'm using MSGARCH package in R. By return_data/Volatility(fit.model), I get the residuals. When I calculate the standard deviation of the residuals, it turns out that it's close to 1 for all residuals. However, the standard deviation in each regime differs greatly. It's about 0.7 in one and 1.6 in the other.
Why is it? I thought that the residuals would have unit variance in each regime respectively, since in each regime they are filtered by a GARCH model.
(This package follows the paper A New Approach to Markov-Switching GARCH Models in model specification.)