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Population-level effects on crime of recovering firearms from armed prohibited persons: intention-to-treat analysis of a pragmatic cluster-randomised trial in California cities

Background

Too little is known about the effectiveness of efforts to prevent firearm violence. We evaluated California’s Armed and Prohibited Persons System (APPS), which identifies legal purchasers of firearms who have become prohibited persons and seeks to recover all firearms and ammunition to which they have access.

Design and methods

This cluster-randomised pragmatic trial was made possible by APPS’s expansion from a small pilot to a continuing statewide programme. We included 363 California cities, allocated to early (n=187) or later (n=176) intervention in blocks stratified by region within the state, and within region by population and violent crime rate. The study period began 1 February 2015; region-specific end dates ranged from 1 May 2015 to 1 February 2016. Analysis was on an intention-to-treat, difference-in-difference basis using generalised linear mixed models and generalised estimating equations with robust SEs. The population-level primary outcome measures were monthly city-level counts of firearm-related homicides, robberies and aggravated assaults. The primary model was adjusted for stratification variables; city-level population, population density, socioeconomic status and firearm purchasing; year; and month.

Findings

Allocation groups were well balanced on baseline characteristics and implementation measures. In adjusted models, allocation to early intervention was not associated with statistically significant differences in any primary outcome measure; these findings were robust to multiple sensitivity analyses. There was some heterogeneity across regions.

Conclusions

The APPS intervention directly affects a very small percentage of the population, limiting its potential for population-level effects. Individual-level analyses may provide a better estimate of the intervention’s effectiveness.

Trial registration number

NCT02318732.

In Search of Common Ground: Expert Judgments on Gun Policy Effects

As our review of the existing literature demonstrated, there is very little scientific evidence available to support the decisions that policymakers and the public must make about whether to implement or change various gun policies. Without strong scientific evidence, policymakers and the public rely heavily on what advocates or social scientists believe the effects of policies are most likely to be. The opinions of these gun policy experts are an important influence on gun policy debates and decisions because people believe that the experts have an especially well-informed understanding of the gun polices under consideration, how similar laws have performed historically, and how specific policies would affect particular stakeholder groups.

Different communities of gun policy experts have sharply divided views on many gun policies, as often becomes clear in the debates that occur when states and the federal government consider new gun legislation. Less clear is whether there are laws or policies for which such differences are less stark, or whether there may be a combination of policies that experts of every stripe could regard as an improvement over existing policies. Finally, it has not been clear whether experts disagree about which objectives gun policies should be trying to achieve or whether experts agree on the objectives but disagree on which policies are most likely to achieve those objectives. If the experts chiefly disagree on the latter, this suggests a role for new and better scientific study of the true effects of gun policies.

To begin to answer these questions, RAND researchers surveyed 173 gun policy experts (across two fieldings in 2016 and 2020) on what they believed the effects of the following 19 gun policies would be on ten different outcomes.

Guns and violence: The enduring impact of crack cocaine markets on young black males

The violence associated with crack cocaine markets in the 1980s and 1990s has repercussions today. Using cross-city variation in when crack cocaine arrived and an older comparison group, we estimate that the US murder rate of black males aged 15–24 was still 70 percent higher 17 years after crack markets had emerged. Using the fraction of gun-related suicides as a proxy for gun availability, we find that increased access to guns led to persistently higher murder rates. Our estimates imply that more guns due to crack-related violence explains approximately one-tenth of the current life-expectancy gap between white and black males.