I have a question about constructing a counterfactual sample.
Using the migplac1 variable, I would like to construct a counterfactual sample (pre- state migration). For example, to make a counterfactual on California, people in California who immigrated one year ago are excluded, and people in other states who were in California one year ago are included. That is, after excluding samples of the California inflows and including those of the outflows into the California observations, the observations are set as the counterfactual.
Is it a valid counterfactual? Hope to hear from you.