Metric Of The Week: Zimring and the Prisoner:Patrolman Ratio

Posted on 25 March 2011 by


The Metric of the Week comes from the forthcoming work of Franklin E Zimring, author of The Great American Crime Decline.

It’s a doozy.

The New York TimesOne Police Plaza blog claimed in early February that the 38-page journal article of Zimring’s forthcoming study of how New York City has seen a remarkable and sustained drop in crime rates since the 1990s, had been leaked by the New York City Police Department’s public relations department.

Whether this is true, it’s certainly a great read.

For the forthcoming article and book, The City that Became Safe: New York and the Future of Crime Control, Zimring compared crime statistics provided by the New York City Police Department with independent sources, such as county health departments (which maintain records of deaths) and auto insurance industry data pools (which maintain records of car thefts).

It’s not that he didn’t trust the NYPD not to play fast and loose with its statistics, it’s just that he didn’t, apparently, trust the NYPD not to play fast and loose with its statistics. In a word.

In The City That Became Safe, Zimring documents that his independent verification tends to support the claims of the NYPD and the city that its extraordinary crime reduction – what Zimring refers to as, “a Guinness Book of World Records crime drop” – is legit. That is just great news on a couple of levels.

The abstract shows some compelling analysis, and is fascinating reading for any analyst – particularly because Zimring states outright that, “the systematic changes which have contributed a major part of the city’s crime decline are not extremely expensive and can be adapted to conditions in other cities. New York shows what is possible in many other cities.” That would be great news, but I’m skeptical about the applicability elsewhere of lessons learned in NYC (see Other Differences, below).

But I want to focus on two aspects of Zimring’s work here, which the author highlights in the last of three paragraphs on “surprises”:

…[T]he city made giant strides toward solving its crime problem without either winning its war on illicit drug use or massive increases in incarceration. So the great success in this city is a challenge to the two dominant assumptions of crime control policy in modern America.

Those two statements are actually fantastically huge in and of themselves, but there’s a giant shocker buried in the thing about incarceration. Before I get there, let’s give some props to another of Zimring’s observations, that the City of New York has, with its “hotspots”* style of policing** imposed a what amounts to a regressive tax (in harm that is physical and mental) on its poor and minority residents – but simultaneously has provided those same poor and minority residents with greater value from their policing.

About 65% of the reduction in homicides in New York were Black and Hispanic men between ages 15 and 44, a group which comprised only 13% of the population. The good news is that lower crime was the one public benefit of the last 20 years which had its greatest impact on the people who needed help the most. The bad news is that the physical and dignitary harms of police aggression also fall the hardest on those who can least afford more trouble from the government.

Now to the wicked-cool stuff:

Reduced Incarceration
The statistic that stands out of Zimring’s work like a Zulu at a Pygmy conference, though, is that the city managed to reduce serious crime by 80% without a net increase in the level of those in secure confinement. Zimring’s interest in this is what he refers to as the game-changing concept that throwing more people in jail to reduce the crime rate is in fact flawed logic. My interest in this is the money.

First, let’s look at the chart Zimring put in his report showing that the New York City incarceration rate – that is, the rate of how often they toss people into the hoosegow city-wide – declined both substantially, and substantially more than the national average from 1990 to 2007.

According to the Justice Policy Institute’s The Dangers of Detention: The Impact of Incarcerating Youth in Detention and Other Secure Facilities, the cost of putting a juvenile in the slammer for a day is $385***. Even if it is substantially less for an adult (I was too lazy to Google beyond this query, which got me not very far), it’s still a metric of interest.

Because the next place that Zimring goes is here:

If three or four fewer prisoners are the equivalent of one more uniformed police officer then 27,000 to 36,000 fewer prisoners could buy the peak period expansion of the New York City police department, and 18,000 fewer prisoners could finance the expansion of the police from the 1990 level to the current rate per 100,000. So the difference between New York City’s incarceration trends and those of the rest of the nation have more than paid for the city’s expanded police force.

Whoa, Nelly. That there is one hot, fresh and delicious metric. I’m not aware of other analysts drawing a metric of

(X-fewer-prisoners) == (Y-more-cops)

are you? Tell me below if you are. I called a coupla analyst friends and they hadn’t either. Zimring’s point seems to be:

  • Non-incarceration of people costs less than incarceration of people.
  • Money not spent on something we now see does not combat crime (like heaving people into the pokey) means that there is more money to spend on things we now see do combat crime (like putting more cops on the street and patrolling aggressively hot spots).

Other differences
Now, I’m a cop in Texas, but I must be clear that I was born and raised in New York City, so when I see statements like, “New York shows what is possible in many other cities.” I get all huffypuffy. After all, to say that New York City is different from everywhere else is also to say that everywhere else is different from New York City. Zimring does a lot of laudable normalization and data cleaning about ethnic breakdowns and other statistical anomalies, but I’m highly suspicious of any paper that can claim to extrapolate a nationally significant thing from a New York City specific thing. After all, just for starters, there’s no place in the country as densely populated as New York City. How do you account for that?

If it can be done, I bet Zimring is the guy to do it. I digress.

All told, this will be one massively anticipated report. And the fewer-prisoners:greater-cops-on-the-street metric is our Metric of the Week.

*An earlier version of this post said, “aggressive patrol-of-hotspots”, which I have now changed to “hotspots” because “aggressive arrests and stops” is a term of art Zimring uses to describe activities of the NYPD that he states are of unknown effectiveness.

** “Aggressive,” Zimring states, is patently not either “zero-tolerance” (he shows that NYPD did not increase arrests for prostitution and was inconsistent in its enforcement of gambling) nor was is “broken windows”. Rather, the NYPD philosophy was the concentrated application of resources into crime hot-spots.

*** In my home county of Tarrant County, TX, the report says, the cost is a relatively reasonable $121, but this goes even farther to prove the point, since cops in Tarrant County are paid substantially less than their NYPD counterparts