Early line on traffic stops leads to more data crunching

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By BILL DWYER

Apparently well aware of Mark Twain's famous caution about "lies, damn lies, and statistics," Oak Park officials are currently pouring over preliminary figures released by the Illinois Department of Transportation (IDOT) related to its Illinois Traffic Stop Study. That statistical study, mandated by 2003 legislation signed into law by Governor Rod Blagojevich, is a 4-year project designed to determine the rate of traffic stops among different ethnic groups as related to their percentage of the general population.

Oak Park Police Chief Rick Tanksley sent a memo to Village Manager Carl Swenson two weeks ago outlining his concerns regarding that data, copies of which were placed in the board meeting packets that village trustees received Monday, June 20, along with the preliminary IDOT figures.

Both Swenson and Tanksley are withholding formal comment until next week, after they've been able to fully assess that data.

Every statistical study features footnotes explaining identifiable anomalies and other factors that may skew final conclusions, and there are several facets of the Traffic Stop Study preliminary data that appear likely to pique Oak Park officials' concern.

Oak Park police conducted a total of 7,737 traffic stops in 2004, with 2,920 being characterized as Caucasian, 1,863 being African American, and 1,062 being Hispanic. The raw data shows that African Americans are over-represented in traffic stops related to their percentage of the general population.

That, however, is where Twain's quip about statistics comes into play. There are at least two "uncontrolled variables," or possible outside causes for the figures that may need to be taken into consideration while discussing the traffic stop figures. For one, Oak Park's immediate proximity to the heavily African-American Austin community may be skewing those "general population" figures. Secondly, the study lumps a wide array of far east and middle-eastern ethnicities under the rubric "Asian," creating a large statistical group comprising 24 percent of the study population.

Oak Park police have received only one complaint alleging racial profiling in the last three years, and that complaint was determined to be unfounded. In January of 2004, Chief Tanksley issued a general order on racial profiling that directed his officers to treat all members of the public "with the respect and dignity they deserve, have come to expect, and to which they are granted under the law."

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