Are Prisoners a Normal Good?

I’ve recently been reading Foucault’s Discipline and Punish, his take on how and why the justice system changed over the course of the Enlightenment from one of public executions and torture to private penitentiaries. His theories are interesting, but it lead me to the question: is incarceration a normal good? In other words, does a country “purchase” more prisoners with more income? Foucault gives several explanations for why over the course of the 18th and 19th centuries prisons increased, but how much of that can be explained by increasing wealth? I decided to look at the numbers and see if I could make any sense of the data (You can see the spreadsheet here, the GDP data is the IMF’s 2008 series and the prison data is from King’s College in London 2008 Prison Population study)

Now, this is a very simple analysis, without controlling for crime levels. Nonetheless, it seems that there is some correlation:

Note that this is without the United States, which is a huge outlier (the U.S. has 756 prisoners per 100,000 citizens, more than 100 more than any other country). And it seems like here there really is a very slight or even no correlation. However, it we look at countries below and above $20,000 of GDP per capita, things look a little different:

Prison Population as Function of GDP for Countries Below $20,000

Here there’s a much clearer correlation. And the same is true when we just look at countries above $20,000:

Prison Population as Function of GDP for countries above $20,000

The same trend seems to be true here: when restricted to countries with similar levels of income, prison is a normal good (and this chart would explode if the U.S. were included). Of course, there are several problems with these charts. $20,000 is a pretty arbitrary number: where would a good cut-off point be? Moreover, both of these charts, and especially the second one, have small sample sizes. Nonetheless,  what does this appear to say about the relationship between incarceration and wealth?

I think this suggests that prisoners are a relative normal good. That is, at the very bottom of the GDP levels, the more wealthy the country is, the more it will imprison its population, because a state wants to reach a certain level of incarceration to protect its citizens – and that level doesn’t get reached until around $20,000 per citizen is reached. At that point, society is at a juncture when imprisoning more people is a cost, and not a benefit. Almost all of the super-wealthy countries imprison fewer people than the relatively wealthy countries below $20,000. However, as GDP increases in wealthy countries, there is some reversal in this position, as its populace as more to lose from crime. Sufficient to say, I’m not quire sure what to make of this situation, which is obviously shaped by trillions of variables besides wealth. Does anyone have any thoughts?

I’ve also looked a bit at how inequality within society influences incarceration rates, and I’ll be posting on that soon.

Photo: From Eastern State Penitentiary, by Christina

This entry was posted in Economics, Law, Politics. Bookmark the permalink.

2 Responses to Are Prisoners a Normal Good?

  1. Pingback: Inequality and Incarceration | Morton and George

  2. Dee says:

    On the other hand, if you plot economic inequity and social mobility against the per capita prison population, the r value is much more significant where increased inequality or decreased mobility equates with increased prisoners. It seems it is most likely not that richer companies have a greater ability to imprison people, it’s that when wealth is concentrated in the top tiers of society and never goes back down, investment to solve social problems that lead to crime are rarely made.

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