The Fragility of Estimated Effects of Unilateral Divorce Laws on Divorce Rates

Following an influential article by Friedberg (1998), Wolfers (2006) explored the sensitivity of Friedberg's results to allowing for dynamics in the response of divorce rates to the adoption of unilateral divorce laws. We in turn explore the sensitivity of Wolfers's results to variations in estimation method and functional form, and we find that the results are extremely fragile. We conclude first that the impact of unilateral divorce laws remains unclear. Second, extending Wolfers's methodological insight about sensitivity of differences-in-differences estimation to allowance for dynamic response, we suggest that identification in differences-in-differences research becomes weaker in the presence of dynamics, especially in the presence of unit-specific time trends.