11:20 - 13:00
P2
Room: Meeting Room 2.3
Panel Session 2
Juraj Medzihorsky - Dealing with Support Violations for Difference-in-Differences
Moritz Marbach - Causal Effects, Migration and Legacy Studies
Nahomi Ichino - Causal Inference for Individual Treatment Effects with Binary Outcomes in Small-N Studies
William Lowe - Unfaithful selectors: The advantages of inducing unfaithfulness for causal inference
Causal Effects, Migration and Legacy Studies
P2-02
Presented by: Moritz Marbach
Moritz Marbach
Texas A&M
Social scientists have long been interested in the persistent effects of history on contemporary behavior and attitudes. To estimate legacy effects, studies typically compare people living in places that were historically exposed to some event and those that were not. Using principal stratification, we provide a formal framework to analyze how migration limits our ability to learn about the persistent effects of history from observed differences between historically exposed and unexposed places. We state the necessary assumptions about movement behavior to causally identify legacy effects. We highlight that these assumptions are strong; therefore, we recommend that legacy studies circumvent bias by collecting data on people's place of residence at the exposure time. Reexamining a study on the persistent effects of US civil-rights protests, we show that observed attitudinal differences between residents and non-residents of historic protest sites are more likely due to migration rather than attitudinal change.