This is a Stata command that helps estimate a treatment effect using the semi-parametric difference-in-difference estimator presented by Alberto Abadie in his seminal paper Abadie, A. (2005), "Semiparametric Difference-in-Differences Estimators", Review of Economic Studies 72, 1-19. 

You can install absdid via the SSC archive by using the following Stata command:

• • ssc install absdid

My web-page at PSE has been discontinued and the database used for the example described in the help file of absdid is no longer available. However you can download it here.