Question: Does the control of concealed carrying (of handguns) have an impact on violent crime?
Hypothesis: Increased control of concealed carrying will cause an increase in violent crime.
Method: Values were assigned to the level of control in a State as follows: 0 for no control, 1 for shall-issue control; 2 for may-issue control; 3 for no-issue control. Data was plotted on two axes: one for all violent crime, one for homicide. Sources: control, homicide, violent crime. Control level was coded by statute, to avoid bias in subjective interpretation of practice. Linear regressions were run for both data series to determine the coefficient of correlation. LibreOffice 3.5.7 was used for charting and calculations.
Results: Both data sets show a weak correlation between increased control and increased rates. R2 for violent crime is .17, for homicide it’s .14. In no case did the least violent State in a group have a lower crime rate in either series than the lowest State in the less restrictive groups.
Conclusion: Restrictions on concealed carry may cause an increase in crime, but other cultural factors are probably more significant in determining the overall difference in crime between States. In no State has increased control lowered crime rates below that of all States with less control – adding control on concealed carry cannot be justified as a valid approach for improving crime rates.