While claiming no great expertise in the matter, I use statistics on a daily basis. Know it or not, we all do.
Every decision we make and every action we take is nested in estimations of probability — estimations that could be expressed in statistical terms. Some things are almost certain to happen: If I take off my socks and let them go, they will most likely fall. Some things have a lessened probability: If I ball up those socks and toss them toward the open hamper, chances are at least one of them won’t make it.
The main point here resides in the fact that I can take both of these actions (sock dropping or tossing) without any kind of formal probability estimate. I don’t need to know my true likelihood of an outcome in order to take action. Of course, as the stakes get higher — jumping in a river, starting a fire, pulling out into traffic — I want to have a much better (but still largely informal) estimation of probability.
Scientists and philosophers use the term "bounded rationality" to describe this process. We’re "rational" in that we use our collected observational data to make informed choices. That rationality is "bounded" because we almost always act with incomplete information (i.e. when we pull into traffic we can’t precisely account for the speed, distance and trajectory of every other vehicle around us). In short, there are always unknowns.
When we move the discussion to crime, the waters get even muddier. Almost everybody can tell you whether they feel safe. Very few people can tell you what their true risk of being a victim of crime is. This distinction is extremely important because we make one of the biggest decisions in life — where to live — based, not in statistical probabilities with extremely tight confidence intervals, but in fuzzy, impressionistic images that are largely qualitative.
My hometown of Pine Bluff provides an excellent example. For decades this community has held the ignominious distinction of having one of the nation’s highest rates of violent crime. Some city council members like to dispute this fact by claiming that people "don’t understand the statistics." My counter claim is that those council members ought to take a math class.
Be that as it may, the 2012 Pine Bluff murder rate is just over 35 murders per 100,000 residents. The national murder rate is something south of 4.8 per 100,000. Simple division tells us that Pine Bluff has a murder rate that’s approximately 7.3 times the national average.
That banging you hear is the sound of "For Sale" signs being driven in front yards … but not so fast. Here’s where bounded rationality becomes important. While the 7.3 figure is important, it doesn’t represent everybody’s true risk of victimization. For instance, if you’re a black male between the ages of 19 and 35, who is involved in illegal narcotics distribution, your true risk is many times higher. Conversely, if you’re an elderly white woman who doesn’t sell drugs, your risk is many times lower.
Despite the empirically demonstrable difference in true risk of victimization, people have fled Pine Bluff like Moses driving a tour bus. Of course, this is understandable because the Chamber of Commerce can’t very well print brochures emblazoned with "Come to PB — Unless you’re a young black drug dealer, you probably won’t be murdered."
That said, bounded rationality has another dimension. We "know" that places with lots of drug-fueled murders also have lots of burglaries, robberies, assaults and all those other crimes for which our old white lady risk index is much higher.
The net effect is like a healthy person sitting in a doctor’s waiting room. When everybody around us appears to be coughing and hacking, we get antsy, no matter when we last had a flu shot.
As for the fortunes of my dear hometown, what we have left are two steep propositions. In the first instance, we must find a way to alter perception. No longer can we afford the moniker of "Crime Bluff." In the second, we have to actually reduce everybody’s true risk of being a victim, no matter their age or skin color.
Matthew Pate is a former law enforcement executive who holds a doctorate in criminal justice from the University of Albany and who has advised police agencies around the country. He writes from Pine Bluff, Ark. Contact him at firstname.lastname@example.org