Mass public shootings have long been a focus of political science research, but new findings suggest previous estimates may be flawed.

This study revisits causal claims about mass shootings by accounting for pre-treatment exposure—a critical factor often overlooked in prior work—using panel data techniques. The authors demonstrate how failing to address this issue can lead to misleading results.

Key Findings

* Accounting for pre-treatment exposure significantly alters estimated effects of relevant factors (e.g., gun laws, societal conditions).

* Standard methods used previously underestimate or misrepresent the true impact under appropriate conditions.

This means that decades of research on mass shootings may be systematically biased due to ignoring early-life risk factors before any intervention occurred.