Guns and crime revisited

I focus on the effect of changes in public security (policing) on private security measures that potential victims can take. In particular, I look at the tradeoff between different types of private security measures – such as using or carrying guns, carrying less cash or keeping less valuables at home, and using burglar alarms or Lojack – and study how this tradeoff is affected by changes in public security. If private householders’ direct security expenses are strongly substitutable with public policing (e.g., for guns which may be more useful in badly policed areas), an increase in policing results in a drop in these expenses; it also results in carrying or keeping less cash (an indirect security measure which reduces the prize a criminal can seize). If, however, householders’ direct security expenses are “complementary” to policing in the sense that they are more effective when police response is rapid (e.g., for burglar alarms), more policing increases these expenses unless the efficacy of joint (public and private) security expenses on combating crime encounters very sharply diminishing returns; moreover, a rise in policing also induces carrying or keeping more cash. An increase in penalties increases the tendency to keep cash on hand, and also reduces crime, provided that as private precautions increase, with policing constant, it takes a larger increment in security spending to compensate for a specific drop in penalties. The results are consistent with some empirical trends in crime rates, policing, penalties and private precautions.