Hi! I wondered if you ever solved this? I have a similar problem where I have aggregate state-level data from 2000-2012 & a policy that was implemented in some states in 2007 and others in 2009. I have a similar dichotomous variable - treatment - which is 1 during treatment years in treated states, and 0 otherwise). The code for my regression is:
xtreg outcome treatment i.year i.state, vce(robust)
For the ritest, I understand I need an interaction variable so that I'm evaluating _b[c.treatment#c.postperiod]. But my problem is, given the postperiod differs between states (sometimes it is 2007+ and sometimes 2009+) & we don't know what it would have been for the control countries, how do I model this? I think I need to program a two-stage randomization process (randomized to control/treatment & randomized to 2007/2009) - but I am struggling with writing this program. Specifically, I can't tie the second randomization (randomization of years in the postperiod variable) into the program properly so that this part of randomization is implemented.
Thanks for any advice!