In his post on incarceration rates, Professor Newquist makes a very interesting observation:
South Dakota has 3,302 prison inmates. [This] seems paltry until one examines how much it costs and compares it with North Dakota's prison population of 1,440. Why South Dakota whose overall population and culture is so similar to North Dakota's incarcerates more than twice the number of people is an issue that has troubled some legislators for decades.
As friend and frequent interlocutor A.I., notes (see comments to my first post), this is a very good question.
I thought the SD vs. ND incarceration rates in Doctor Newquist's post were thought provoking. As he asked, why the great difference between the two states? And, if you do the math, the rate in SD is about 1 in 230 as opposed to ND at about 1 in 475. Seems to me we should try to determine why. Does ND suffer more crime because less people are in prison? If not, does SD have more (seamy) people, are our sentencing practices or laws too stringent, etc.?/Maybe it has to do with northern climbs, meaning the entire prison population of Manitoba and Saskatchewan might fit in one of our county jails while Texans would...
That's the kind of comment that comment sections are for. I don't know how to answer the question, like that's going to stop me. It does seem to me that the obvious first question is whether crime rates differ between the two states. If not, then I suppose it has to do with sentencing. If so, then the question is whether the differential explains it, and how to interpret the causation.
The U.S. Census Bureau has some helpful numbers.
Violent Crimes/100,000 people | 2005 | 2006 |
North Dakota | 111 | 128 |
South Dakota | 179 | 171 |
Property Crimes/100,00 people | ||
North Dakota | 2,025 | 2,000 |
South Dakota | 1,767 | 1,620 |
Now those are interesting stats. Since the numbers control for population differences, it would appear that North Dakotans are both less violent on average and less respectful of their neighbor's property. Them's no small potatoes.
Now I am pretty sure that violent crimes (e.g., murder and rape) are more likely to draw a prison sentence than property crimes. I would also note that prison sentences average about 2 years and may be well longer than two years. This year's convictions will add to the incarceration rate for several years to come. So a significant differential in the violent crime rate between two states will result in a more significant difference in incarceration rates over time. A violent crime rate differential of 111 vs. 179 is quite robust.
Have I answered Professor Newquist's provocative question? Maybe. A lot more analysis would have to be done on the numbers to be sure. But A.I. suggests another problem: if South Dakota is locking up more people, but has a higher violent crime rate, doesn't that mean that incarceration doesn't work? Here we have a problem of correlation vs. causation. Consider: we spend a lot more money on medical care for octogenarians than for teenagers, but the former suffer from more diseases. Does this mean that the medical care isn't working? In a sense, yes; but the underlying causation is due to aging.
If South Dakota reduced its incarceration rate, what would happen? That depends on how effective that rate is in suppressing crime. None of these numbers help us with that. All we know is that, in specific places, increasing incarceration rates correlate with decreases in the crime rate.
So maybe the real question is why less violent crime but more property crime in North Dakota. Here, Professor Newquist has me stumped.
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