Home > Crime Rates, Stop-and-Frisk > Stop-and-Frisk and the New York City Murder Rate

Stop-and-Frisk and the New York City Murder Rate

New York City just elected a new mayor who has expressed skepticism about the Stop-and-Frisk policy of the New York City Police Department. There has been some press reporting of this situation and I thought it might be instructive to gather some data just to see what the data might reveal about the Stop-and Frisk policy.

One of the truly amazing innovations brought by the internet to economists with empirical interests is how easy it is to gather data. After a one minute Google search, I found the FBI web site (www.fbi.gov) providing data on U.S. crime rates. Their data collection program, Uniform Crime Reports, contains data on crime rates by city among other things and so I downloaded murder rate statistics for New York City.

One last piece of data was needed for our analysis and that is the date when Stop-and-Frisk was started. Another great innovation, Wikipedia, provides the answer. An article there states that the program started under Mayor David Dinkins during the 1990-1993 time period. With this last piece of data, we can now see what the data might reveal about the effectiveness of the Stop-and-Frisk program.

The chart given here plots the annual murder rate per 100,000 residents in New York from 1985 to 2012. Over this

NYC_Murder_Ratetime period, the chart reveals the substantial decline in the murder rate starting almost exactly in 1990. Thus it is not surprising that the head of the New York City Police Department thinks that Stop-and-Frisk has saved lives. The data sure make it seem so. But is this really true?

Economists are sometimes criticized for having too many hands (that is, they say “on the other hand” much too often) but, being careful folks, economists usually wonder why data can be misleading about the underlying causality that seems evident in data. It is instructive to ask why the chart may be misleading.

Caveats

The most important qualification that comes to mind is that there are other forces at work which might be the true causes of the decline in the murder rate. For example, it has been suggested that demographics are the true reason for the reduced murder rate because, over this time period, there was a decline in the people most inclined to commit violent crimes. In addition, there can be measurement error in the data, the Stop-and-Frisk program may not really have gotten under way in 1990, and there may be other reasons why the chart is misleading. So it seems prudent to say that the data is suggestive but not decisive even though it seems to back the position of those who support Stop-and-Frisk.

What Would You Do?

Policymaking is often very difficult even when it is done by the most competent people and here we are talking about a policy affecting the lives of New York’s citizens and any policy changes could in fact result in the deaths of individuals living in New York City. Playing amateur criminologist, as we have done here, can be fun but changing Stop-and-Frisk is a very serious business. What would you do if you were the new mayor of New York? Would you be willing to change a policy like Stop-and-Frisk and take responsibility for the deaths that might result? I will leave it to you to ponder that question.

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A blog by John B. Taylor

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