I built a DSGE model to compare the effects of several monetary policies.
The welfare loss function is in the form of Woodford (2003) and Galí and Monacelli（2005）.
I bulit a m.file in matlab：
“- (1- alpha)/2 beta ( epsilon/lambda * oo_.var(3,3) + (1+ phi)*oo_.var(2,2) )”
I have two questions as following.
（1）Numerical value of oo_.var are a little different according to different times of MH algorithm.
How much times should MH algorithm be? 10000 times？or 250 times？
（2）I’m not familiar with welfare analysis，so ask a basic question. In some articles，they also did different types of shocks on welfare losses，for example ， technology shocks ，monetary policy shocks, etc（I’m not sure whether other shocks are not taken into account, only taking one kind shocks ?）. I want to ask them how they did it. oo_.var has only one aggregate volatility？
Thank you in advance for answering my questions.