In the hope of contributing something constructive to the argument about the benefits of having armed civilians in the public square and schools, I would like to try a sort of risk-benefit analysis.
To measure “benefit” we need to determine the likelihood that you can successfully intervene, using a gun, if you or someone near you becomes a victim of a violent crime in a situation that would validate the defense of justifiable homicide under New Mexico law.
The FBI reports that the rate of violent crime in New Mexico in 2010 was 589 crimes per 100,000 population; the national rate was 404.
The 2008 National Crime Victimization Survey (latest available) says that there were 4,856,510 victims of violent crimes that year, a rate of 1,595 per 100,000 population.
A valid rough guess might be that the probability of becoming a victim is around 1,000 per 100,000 per year.
Because you may defend another as well as yourself, you have to add in the probability of being near another victim.
To try to account for that let’s just add another 1,000. So the probability of an opportunity to realize a benefit of carrying a gun is about 2,000 per 100,000 per year, or 2 percent per year.
At that rate most of the people who carry firearms can expect to have one benefit occur in their lifetime.