Difference-in-differences Matching I have a difference-in-differences analysis. My treatment is at the county level. Each county received the treatment at a certain point in time. 

I want to proceed with a propensity score matching as an extension to get DiD-matching results . I know everything about PSM, however, I am not quite sure how to get the STATA command in order to:


Generate Pre- and Post-treatment dummies since I don't have a
treatment at one point in time; i.e. DD is staggered.
Use the DD with pscore
You can use mark. For example, if the treatment was done in the year 2000, and your time variable is called time, the syntax is

mark treatment if time &gt;= 2000 &amp; time &lt;.

where treatment is the dummy that is generated.