I have a panel data set covering various countries over various years. I have information about the years in which these countries published an entrepreneurship policy - some countries only published one in the past 20 years, while others published a new one every five or ten years. I also have an annual estimate of the level of entrepreneurial activity for each country.
I'd like to evaluate whether the launch of these policy documents resulted in an increase of entrepreneurial activity in these countries. However, I am not sure how to approach this question methodologically, since the policies were introduced in different years and sometimes countries introduced various policies over the time that my data set covers.
I don't think I can use the typical methods for evaluating the impact of treatment (such as difference-in-difference and instrumental variables regression), since the introduction of a treatment, which in my case is the introduction of policies take place across different years and sometimes there are several "treatments" for individual countries.
I would greatly appreciate your help with this question, as I am stuck not having found guidance searching through my books and the existing questions on Cross Validated.