Table 1.

Types of Analytic Approaches to Address Policy Co-Occurrence and Corresponding Causal Research Questions

Analytic Approach	Corresponding Causal Research Question
Effect of individual policy of interest
1. Adjust for co-occurring policies	What is the effect of the policy of interest on the health outcome?
2. Restrict the study sample to the region of common support	What is the effect of the policy of interest on the health outcome in the restricted sample?
3. Define the outcome on subpopulations likely to be affected by the index policy but not other co-occurring policies	What is the effect of the policy of interest on the health outcome in the subpopulation?
4. Select a less-correlated measure of policy exposure	Example: How does a more generous version of the policy of interest affect the health outcome, compared with a less generous version of the policy interest?
5. Use formal Bayesian methods	What is the best estimate of the effect of the policy of interest on the health outcome, considering both prior knowledge on policy effects and the observed data on policies and outcomes?
Combined effects of multiple policies
6. Identify and evaluate the impacts of policy clusters	Example: What is the effect of adopting all policies in the cluster vs. no policies in the cluster on the health outcome?
7. Use an overall policy stringency or generosity score	What is the effect of differing levels of overall policy stringency or generosity on the health outcome?