A few years back, after a one-day class with information-design rock star Edward Tufte, I decided to try my hand at creating a complex infographic by charting violent crime rates in different states against a number of variables, including strictness of gun control laws, poverty rate, and diversity. The biggest problem with this attempt was that it contained no temporal index. My father, an ardent gun-rights supporter, suggested that I look instead at how crime rates change after laws prohibiting the carrying of concealed weapons are repealed; the argument from gun-rights advocates, of course, is that if criminals are unsure who might be carrying a weapon then everyone is less likely to be the victim of crime. I decided to take him up on the proposition, and have spent the last year or so working on the graphics displayed below. Little did I know that by the time I was finished with them, the Seventh Circuit would have struck down Illinois’ status as the last state with a total ban on concealed carry or that the nation would be embroiled in a passionate debate over the place of guns within our society after Newtown.
I should state at the outset that my interest in creating these images is less in influencing social policy — I am not naive enough to think that I have much chance in doing that — than in testing my ability to communicate information about large amounts of data. I also recognize that, not being a statistician, there are certainly more sophisticated ways of analyzing the same data that I have examined here; should this post happen to inspire someone with more statistical chops to check my findings, so much the better. All of that said, I think the data I’ve accumulated here (also available in this spreadsheet) speaks pretty powerfully to the question of whether permitting citzens to carry concealed weapons has a deterrent effect on violent crime.
A few notes on sources and terminology: stats on violent crime are easy to find via the FBI, but it is surprisingly difficult to find official information about when changes in gun laws have been made. The closest I could find to a comprehensive survey of changes in concealed carry laws was the cheekily named pro-gun site Radical Gun Nuttery!, which provides a list of dates and a (partial) list of citations for those dates. States are ranked as having concealed carry laws that fall into one of four classifications:
- no-issue (allows no private citizen to carry a concealed weapon)
- may-issue (allows concealed carry with a permit that may be granted at the discretion of some local government office)
- shall-issue (acquiring a permit only requires meeting a predetermined set of criteria)
- unrestricted (no permit required)
- National average increased, state average decreased: 1 (OR)
- National average decreased, state average decreased more: 2 (KY, TX)
- National average increased, state average increased less: 1 (PA)
- National average decreased, state average increased: 6 (AK, OH, CO, MN, TN, UT)
- National average increased, state average increased more: 6 (MS, ID, FL, GA, MT, WV)
- National average decreased, state average decreased less: 11 (AR, AZ, OK, MO, NC, SC, NM, LA, MI, NV, VA)
So… what do you think of these graphics? How could they, or the data communicated in them, be improved?