I'm using Stata 14 with Windows 10 OS.

I'm running PSM diff-in-diff using command diff. I'd like to test if for the same group, that was a significant change of mean after the event.

I can see on Stata help that several scalars are saved on r() after running regressions. Among them, that is mean of output-var for control and treated groups before and after event. That is also standard errors.

Does anyone have an idea about how to perform such test?