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NU profiling study really proves nothing

TO THE TORTURED subject of racial profiling, a recent study by Northeastern University is said to add new evidence. But does it?

University researchers found small racial disparities in traffic citations issued by 249 Bay State police departments. The findings have been greeted as proof of police bias. This conclusion is at best premature, since the Northeastern study lacks every prerequisite of sound profiling analysis.

To the claim that the police stop "too many" members of any given demographic group, the question must always be: "too many" compared to what? The Northeastern study compares police stop rates to population demographics. If 7 percent of a town's residents are black, for example, but 8 percent of traffic citations issued by the town's police are for black drivers, the authors conclude that the police single out drivers on the basis of skin color.

But population is a flawed benchmark for analyzing police actions -- as if police officers are guided by the census rather than by behavior. Crime rates differ across racial and ethnic groups; evidence suggests that driving behavior might, too. A 2001 study of the New Jersey Turnpike, for example, found that black drivers were twice as likely to speed as white drivers, a disparity that increased at speeds above 90 miles per hour. There are many possible explanations for this difference: Black drivers may be more likely to travel long distances on the turnpike, bringing them more frequently into faster left-hand lanes, or the black population on the pike may contain more young males than the white population, raising the number of speeders as well. The Northeastern study makes no effort to determine driving habits among its target groups; it thus has no basis for judging whether police stop rates are disproportionate.

Driving patterns are just the start of valid profiling analysis. Different levels of equipment violations, such as broken taillights and missing vehicle registration tags, must be accounted for as well. Poor people have to defer required repairs more often than the affluent, and poverty is concentrated in minority populations. No word from the Massachusetts study on this factor, however.

Next question: Who's on the road when? Highway populations can vary wildly according to time of day and day of the week. If more police are on patrol when the proportion of minority drivers is highest -- on weekend nights, for example -- stop rates of those drivers will perforce be higher than the average road population would predict. Northeastern's method for determining road demographics is laughable -- in most cases extrapolated from such alleged predictors as local restaurant and hotel receipts -- and is no substitute for hour by hour observation of traffic and police deployment.

Most egregiously, the profiling researchers ignore the relationship between community crime rates and police presence. Calls from crime victims bring officers disproportionately into minority neighborhoods, because that is where violence is highest. Responsive commanders will target policing strategies in those same neighborhoods, to protect the most vulnerable residents. A greater police presence in an area usually produces more citations.

A reliable model of police discretion requires many more variables; the Northeastern team does not even hint at them. To now order Massachusetts officers to collect racial data, without developing a valid benchmark for that data, is senseless -- even more so given how minute the disparities measured by the recent study are. Cops will waste countless hours filling out forms that no one knows how to analyze, and they may think twice before stopping minority violators, lest they be accused of racism.

As usual, the ultimate victims of this groundless crusade will be law-abiding members of inner-city neighborhoods, who depend on an energized police force to keep them safe. There may be isolated officers who violate their oath of impartiality, to the disgrace of their profession, but no one has ever produced evidence that the vast majority of cops use skin color, rather than behavior, to determine whom they stop, cite, or arrest. With their every move being analyzed through the prism of race, however, officers may well start to calculate their actions in terms of black and white.

Heather MacDonald is a fellow at the Manhattan Institute and the author of "Are Cops Racist?"  

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