Yes, the generalizability theory can be used appropriately to analyze the effectiveness of the Affordable Care Act, because we have to be able to analyze public policy as it pertains to the most amount of people. The public good is what helps the most people, so generalizability is a fair way to look at the ACA.
The generalizability theory can be used to test the reliability of the overall Affordable Care Act by taking into account all facets of the law. The theory can assess how many people sign up, how premiums rise or fall and whether or not the overall economy improves. In general, the ACA can be a pass/fail based upon the generalizability theory.
Yes, the generalizability theory can be used to analyze the effectiveness of the ACA because if individuals are having great results with it, in general, then that is an indicator that it's working. It can be seen in many things and not solely the ACA. Once the legislation starts playing out more, it'll certainly be something that can be analyzed for effectiveness through the theory.
I do not believe the generalizability theory can be used appropriately to analyze the effectiveness of the Affordable Care Act. The effectiveness of the Affordable Care Act will not be known for several years and trying to crudely calculate its effectiveness will only provide projections and estimates, of which we can not truly evaluate. We'll simply have to wait for the results which could impact whole generations differently.