Working Paper: NBER ID: w21459
Authors: Rajeev Dehejia; Cristian Popeleches; Cyrus Samii
Abstract: We study issues related to external validity for treatment effects using over 100 replications of the Angrist and Evans (1998) natural experiment on the effects of sibling sex composition on fertility and labor supply. The replications are based on census data from around the world going back to 1960. We decompose sources of error in predicting treatment effects in external contexts in terms of macro and micro sources of variation. In our empirical setting, we find that macro covariates dominate over micro covariates for reducing errors in predicting treatments, an issue that past studies of external validity have been unable to evaluate. We develop methods for two applications to evidence-based decision-making, including determining where to locate an experiment and whether policy-makers should commission new experiments or rely on an existing evidence base for making a policy decision.
Keywords: external validity; fertility; natural experiment; treatment effects; policy implications
JEL Codes: C18; C31; C9; F63; J13
Edges that are evidenced by causal inference methods are in orange, and the rest are in light blue.
| Cause | Effect |
|---|---|
| Macro covariates (E16) | Treatment effect heterogeneity (C21) |
| Sibling sex composition (J12) | Incremental fertility (J13) |
| Sibling sex composition (J12) | Mother's labor supply decisions (J22) |
| Incremental fertility (J13) | Mother's labor supply decisions (J22) |