The academic (and public) debate on the impact of conceal-carry laws on crime rates persists. In 2004, the National Research Council ("NRC") evaluated the "More Guns, Less Crime" hypothesis. In The Impact of Right to Carry Laws and the NRC Report: The Latest Lessons for the Empirical Evaluation of Law and Policy, Abhay Aneja (Stanford), John Donohue (Stanford), and Alexandria Zhang (Johns Hopkins) re-analyze and expand the NRC study. An excerpted abstract follows.
"We evaluate the NRC evidence, and improve and expand on the report’s county data analysis by analyzing an additional six years of county data as well as state panel data for the period 1979-2010. We also present evidence using both a more plausible version of the Lott and Mustard specification, as well as our own preferred specification (which, unlike the Lott and Mustard model presented in the NRC report, does control for rates of incarceration and police). While we have considerable sympathy with the NRC’s majority view about the difficulty of drawing conclusions from simple panel data models and re-affirm its finding that the conclusion of the dissenting panel member that RTC ["Right-To-Carry"] laws reduce murder has no statistical support, we disagree with the NRC report’s judgment on one methodological point: the NRC report states that cluster adjustments to correct for serial correlation are not needed in these panel data regressions, but our randomization tests show that without such adjustments the Type 1 error soars to 22-73 percent."