OBJECTIVE In this study, we analyzed the relationship between state firearm laws and the incidence and severity (i.e., number of victims) of mass public shootings in the United States during the period 1976-2018. HYPOTHESES We hypothesized that states requiring permits to purchase firearms would have a lower incidence of mass public shootings than states not requiring permits. We also hypothesized that states banning large-capacity ammunition magazines would experience a lower number of victims in mass public shootings that did occur than states without bans. METHOD We developed a panel of annual, state-specific data on firearm laws and mass public shooting events and victim counts. We used a generalized estimating equations logistic regression to examine the relationship between eight state firearm laws and the likelihood of a mass public shooting. We then used a zero-inflated negative binomial model to assess the relationship between these laws and the number of fatalities and nonfatal injuries in these incidents. RESULTS State laws requiring a permit to purchase a firearm were associated with 60% lower odds of a mass public shooting occurring (95% confidence interval [CI: -32%, -76%]). Large-capacity magazine bans were associated with 38% fewer fatalities (95% CI [-12%, -57%]) and 77% fewer nonfatal injuries (95% CI [-43%, -91%]) when a mass shooting occurred. CONCLUSION Laws requiring permits to purchase a gun are associated with a lower incidence of mass public shootings, and bans on large capacity magazines are associated with fewer fatalities and nonfatal injuries when such events do occur. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

中文翻译：

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1976-2018年间，州枪支法与美国大规模枪击事件的发生率和严重性之间的关系。

目的在本研究中，我们分析了州枪支法律与1976-2018年期间美国大规模公共枪击事件的发生率和严重性（即受害者人数）之间的关系。假设我们假设，需要许可证购买枪支的州与不需要许可证的州相比，发生集体枪击事件的发生率要低。我们还假设，与没有禁止令的州相比，禁止大容量弹药杂志的州在发生的大规模公共枪击事件中遇难人数要少。方法我们开发了一组年度特定州数据，涉及枪支法，大众枪击事件和受害人数。我们使用广义估计方程逻辑回归分析了八种州枪支法律与大规模枪击可能性之间的关系。然后，我们使用零膨胀负二项式模型来评估这些法律与这些事件中的死亡人数和非致命伤人数之间的关系。结果要求购买枪支许可证的州法律与发生大规模公众射击的机率降低60％相关（95％置信区间[CI：-32％，-76％]）。大规模射击时，大容量杂志禁令的死亡人数减少38％（95％CI [-12％，-57％]），非致命伤害减少77％（95％CI [-43％，-91％]）发生。结论法律要求购买枪支，这与大众枪击事件的发生率较低有关，发生此类事件时，禁止使用大容量杂志会减少死亡和非致命伤害。（PsycInfo数据库记录（c）2020 APA，保留所有权利）。