Difference-in-differences with two policies Can I use the general DiD approach with two policy variables (i.e., two treatments) as below?
xtreg outcome i.policy_1 i.policy_2 i.year, fe vce(cluster id)


Your post doesn't say what type of data you're working with or what these treatments actually represent. But, in general, if the specifics of your study meet the requirements of the 'generalized' difference-in-differences estimator, then this approach may accommodate two policy dummies to represent the different treatments. Depending upon the circumstances, you may even suspect a synergy between the two treatments, in which case it is permissible to interact the two policy variables.
