Empirical Challenges in Defining Treatments and Time in the Evaluation of Gun Laws

Article Public, Environmental & Occupational Health

The Era of Progress on Gun Mortality: State Gun Regulations and Gun Deaths from 1991 to 2016

Patrick Sharkey et al.

Summary: This article provides evidence that restrictive state gun policies implemented from 1991 to 2016 in the United States have been effective in reducing gun mortality. The study finds a strong and consistent association between the number of restrictive gun regulations passed by states and a decrease in overall gun deaths, gun homicides, and gun suicides. Specific policies, such as background checks and waiting periods for gun purchases, were found to be particularly effective.

EPIDEMIOLOGY (2023)

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Article Economics

Estimating dynamic treatment effects in event studies with heterogeneous treatment effects

Liyang Sun et al.

Summary: In settings with variation in treatment timing across units, coefficient on a given lead or lag can be contaminated by effects from other periods in two-way fixed effects regressions, and apparent pretrends can arise solely from treatment effects heterogeneity. An alternative estimator free of contamination is proposed, and the relative shortcomings of two-way fixed effects regressions with leads and lags are illustrated through an empirical application.

JOURNAL OF ECONOMETRICS (2021)

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Article Economics

Difference-in-differences with variation in treatment timing

Andrew Goodman-Bacon

Summary: The paper explores the relationship between the two-way fixed effects estimator and all possible two-group/two-period DD estimators, showing that it is a weighted average. A causal interpretation of two-way fixed effects DD estimates requires meeting the parallel trends assumption and constant treatment effects over time.

JOURNAL OF ECONOMETRICS (2021)

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Article Multidisciplinary Sciences