Monday, June 14, 2010

Minneapolis Murder Rate - Now With Math

After (another) spate of shootings, the city of Minneapolis is "up" to 24 for the year. It was only months ago that R.T. Rybak declared victory on crime. Touting the success of his youth programs, he removed cops from the streets and ran for governor.

What happened? Have the youth programs ceased to perform? Journalists and the mayor's office are baffled. They shouldn't be. Here's why.

From 2000-2009, Minneapolis averaged 45.1 homicides per year, with a standard deviation of 10.8. Over the last four years, the numbers have been even more erratic, with 41.3 murders and a SV of 17.2.

Wait! Come back! The maths will not harm you.

What this means is that, simply by looking at the numbers, an objective observer (we'll call him Ralph) would predict, with 95% confidence, a range of 34-56 homicides based on the data of the last ten years, or a range of 24-58 based on the last four. For discussion's sake, let's split the difference and go with an expectation of 29-57.

Ralph wouldn't be terribly surprised by the city's present projected pace of 53 homicides. He would have been baffled, however, by last year's 19 figure, having projected a narrow range of 42-54 based on a ten year data set. Ralph could also be forgiven for concluding that, given such an outlier, it would not be unreasonable to expect a further diminution of the homicide rate.

Clearly, this was Rybak's calculus as well, but let's dig deeper. Below are the homicide numbers for each of the last five years.

2005 - 47
2006 - 60
2007 - 47
2008 - 39
2009 - 19

Within four years, we had both the highest and lowest data points since 1996.

Let's think about what happens during a homicide. Someone dies, right? Also, at least one other person becomes guilty of murder. Who murders? Why, murderers, of course. Who gets murdered? Those who draw the ire of murderers.

In 2006, then, we had a lot of murderers acting on their impulses, and a lot of people hostile to murderers falling victim to same. Approximately half of murders in Minneapolis are gang and drug related. In other words, about half of those murdered are likely, if left unmurdered, to murder someone else. Further, those who murder get arrested, often along with a bevy of accomplices, who are also nascent murderers.

2006 took a lot of murderers off the streets.

What happens when you take murderers off the streets? They can't murder any more. That is why you put cops on the streets... To take murderers off of them.

Over time, however, those murderers come back. Accomplices cut deals in exchange for short sentences (think gun possession, which carries essentially no penalty in the state of MN). New grudges and turf wars emerge.

Does that get us from 19 to 53? Probably not. Yet.

Consider foreclosures. The vast majority of foreclosures in Minneapolis were confined to the city's north side, where (not coincidentally) most violent crimes also occur.

Many drug and gang houses are owned by the sort of absentee landlords who simply have too many properties to manage. The housing bust was particularly unkind to these property owners, leaving plenty of the most potentially violent offenders to find new digs, while depriving them of many of their local clientele. If recent shootings on the south side are any indication, these thugs are just now beginning to discover all the city has to offer.

Which brings us back to Rybak. Based on the information above, an astute city leader would double down on enforcement. Alas, at the precise moment having more cops on the streets would have had maximum impact, Rybak called in the forces and ran for governor. I could have told him that was a bad idea. In fact, I did tell him that.

All of which is utterly depressing. For a city of Minneapolis' size and relative affluence, 19 homicides per year is about right. But R.T. Rybak has not created the conditions for continued crime abatement. He has paid the political price for his clueless arrogance, while the rest of us sacrifice our ongoing safety.














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