Tuesday, September 23, 2014

Income and disparity

Yesterday, I discussed the impact of police deployment practices on the racial disparity apparent in traffic stops by the Lincoln Police Department. Today, I am focusing on the Big Dog: income. More than any other factor, racial differences in income influence disparity in traffic stops.

Back in 2003, I wanted to explore this possibility. I obtained an export from our records management system of all traffic tickets written by LPD officers the preceding year, 2002, then dropped those data into an Excel spreadsheet. Using pivot tables, I produced counts and queries by offense type. The racial disparity for some offense types, such as driving while suspended, fictitious plates, no insurance, and improper registration, was exceptionally large: a factor of four or five for African-American motorists compared to population.

For the most common traffic offense, speeding, there was no racial disparity in the 2002 traffic citation data. The most disparate offenses were all related to one's ability to buy insurance, pay registration fees and taxes, pay fines, reinstatement fees, and the like. These income-related offenses were driving the overall disparity. I did the same thing the following year with 2003 data, then again last week with the over 50,000 traffic charges from 2013. Basically, the same results emerge by offense type, looking at tens of thousands of tickets.

I also did some work using the field in the data for the model year of the vehicle. I reasoned that the model year of the vehicle might be a rough indicator of income, and my thought was to use it as a stand-in variable. When you look at late-model vehicles--those in the most recent five model years--racial disparity pretty much evaporates.

I think these findings are intriguing, and suggest a significant influence of income on racial disparity in traffic stops. Research Methods was one of my toughest courses in grad school, and I'm no PhD. I have discussed my ideas and offered these data for a decade to several people who are, however, including faculty members in the University of Nebraska at Omaha School of Criminology and Criminal Justice, from which I am a graduate.

Every academician I've talked to about this has been interested in what I have found, but so far there have been no takers. Last week, after reading the news that Attorney General Eric Holder announced a major Federal research effort on racial profiling, I contacted the portfolio manager for that research at DOJ with yet another offer. We shall see. All law enforcement agencies collect the offense type and the model year of the vehicle on their traffic tickets. The work I've done in Lincoln could be repeated almost anywhere, and a broader sample might provide more insight into how income affects racial disparity in traffic stops.

Here's why this is important: if most of the racial disparity is the result of income differences, we are barking up the wrong tree trying to fix it with the usual formula: screening police applicants for signs of racism, implicit bias training for officers, enhanced accountability systems, and so forth. This doesn't mean these steps have no value (they are valuable in their own right), but they are not likely to impact disparity because they are not related to its cause.

It is worth noting that racial disparity in police traffic stops is only the tip of the iceberg. We live in a country where there is huge racial disparity in educational outcomes, income, incarceration, health, and even life expectancy. Deal with the first one, educational outcomes, and the others will largely disappear over time. That's what I've been advocating.

Links to the series:



Anonymous said...

Looks to me the only way to stop appearant profiling or racial disparity is to bow down to the ACLU and quit enforcing traffic laws against minorities.

Anonymous said...

We live in a country where there is huge racial disparity in educational outcomes, income, incarceration, health, and even life expectancy.

How do we account for the disparities in education, income, incarceration, health, and life expectancy between, for instance, Blacks and East Asians?

Also, there are a lot of people whose entire career and sometimes considerable income depends on the existence of racial discrimination in policing, sentencing, and incarceration, or at least the perception of its existence, and they'd be sure to willfully disregard any research that endangered their rice bowl. In other words, their mission can't be completed, because then they'd be out of a job. In this category you could group some academics, political activists, and elected officials.

Anonymous said...

You nailed it. Education is the key to solving a large part of our crime problems.

I am going off topic now but I see this as part of our crime problem. I worked at our State Penitentiary for ten years. One of the things that really amazed me was the illiteracy rate among the inmates. I don't have any data to back this up but I would guess that at least 40% of the inmates read and write at a fourth grade (or lower) level.

The flip side of that coin is the number of inmates that have achieved high levels of education. Instead of letting these inmates walk the yard for fifteen (+/-?) hours a day maybe someone in corrections could work out a program that uses some of the inmates to TEACH other inmates various skills. Not advanced auto theft or safe cracking but the basic three Rs.

They have or had a program that allows inmates to train service dogs and then offer the dogs to the public. A great program BUT if they can have inmates teaching dogs maybe they can come up with a program to educate other inmates.

The department of corrections is under the gun right now because of the stupidity of a few in upper administrative jobs. Maybe when this all shakes out they can replace these idiots with some staff who can actually get something done.

Gun Nut

Tom Casady said...


A couple hundred years of slavery, followed by another hundred years of pernicious racism doesn't evaporate in a single lifetime. It continues to reverberate for several generations.

Steve said...


I agree to some extent that slavery and discrimination have a role in the disparities we still see today. On the other hand, there are plenty of blacks, or other minorities, that have overcome the legacy to which they were born. I suspect that it is not solely the economic and social circumstances you are born into that determine your ability or willingness to succeed and to abide by the laws. I would also imagine that, in Nebraska at least, there are more poor white people than the total number of black people. I could be wrong on that, but given that, except perhaps in Omaha, blacks are a fairly small minority in Nebraska, there are at least a comparable number of whites living in poverty. That being the case, you'd expect that if economic status was a significant factor in crime, the imbalance would not be as significant as it is.