(where concealed carry permits must be given if criteria are met) "are associated with significantly higher rates of total, firearm-related, and handgun-related homicide" than "may-issue laws" (where local law enforcement have discretion over who can get a concealed carry permit). A 2011 study found that aggravated assaults increase when concealed carry laws are adopted. A 2019 study in Journal of American College of Surgeons found "no statistically significant association between the liberalization of state level firearm carry legislation over the last 30 years and the rates of homicides or other violent crime." This is also in line with a 1997 study researching county level data from 1977 to 1992 concluding that allowing citizens to carry concealed weapons deters violent crimes and it appears to produce no increase in accidental deaths. A 2018 study in The Review of Economics and Statistics found that the impact of right-to-carry laws was mixed and changed over time. RTC laws increased some crimes over some periods while decreasing other crimes over other periods. The study suggested that conclusions drawn in other studies are highly dependent on the time periods that are studied, the types of models that are adopted and the assumptions that are made. A 2015 study that looked at issuance rates of concealed-carry permits and changes in violent crime by county-level in four shall-issue states found no increases or decreases in violent crime rates with changes in permit issuances. A 2019 study in the International Review of Law and Economics found that with one method, right-to-carry laws had no impact on violent crime, but with another method led to an increase in violent crime; neither method showed that right-to-carry laws led to a reduction in crime. A 2003 study found no significant changes in violent crime rates amongst 58 Florida counties with increases of concealed-carry permits. A 2004 study found no significant association between homicide rates and shall-issue concealed carry laws. A 2013 study of eight years of Texas data found that concealed handgun licensees were much less likely to be convicted of crimes than were nonlicensees. The same study found that licensees' convictions were more likely to be for less common crimes, "such as sexual offenses, gun offenses, or offenses involving a death." A 2020 study in Applied Economics Letters examining concealed-carry permits per capita by state found a significant negative effect on violent crime rates. A 2016 study found a significant