A new study demonstrates that the so-called "driving while black" phenomenon is not supported by the data in Massachusetts. The study uses a "veil of darkness" approach to estimating racial bias. If the rate of pulling over blacks rises during daylight hours, when police can see the race of the driver, and falls during night-time hours, when they cannot, then that would suggest there is a racial bias in their decision of whether to pull over a car. By looking specifically at the “Inter Twilight Period”—the period that is dark for part of the year and light for the other—it was even possible to compare results at the same time of day with substantially similar driving conditions but in different lighting.
In contrast to the theory underlying the term “driving while black,” what they discovered was that police have a statistically significant bias towards pulling over white drivers. The report says this means that "no support was shown for a pattern of racial disparity". That’s a bizarre, but revealing, conclusion. They literally just proved racial bias. (Or, is there another possible explanation of their findings? I can't think of one.) But because they believe the racial bias they found hurts whites, they conclude by stating the exact opposite of what their data showed: there is no racial bias. Apparently, the study’s authors believe racial bias exists only where it hurts minorities.
In a moment, I’ll consider who is really hurt by a failure to apply laws encouraging safe driving equally to blacks, but first it's worth considering how another finding of the study was covered by corporate news media. The study found that, once pulled over, black and hispanic drivers were more likely to be searched and given a citation, a fact that the Boston Globe used to argue that the study was actually “further documentation of inequities in the justice system”. The newspaper makes no mention of the fact that a higher rate of searches and citations does not in any way suggest police bias, and therefore does nothing to suggest inequities in the justice system.
To see why it does not, consider that blacks account for 16% of stopped drivers, but only 9% of state residents, and whites account for only 65% of stopped drivers while they make up 80.6% of state residents. So, blacks are pulled over at a much higher rate than whites, even though the study proved that when police can identify the race of the driver they pull over blacks less often, demonstrating bias against pulling over blacks. What could explain why blacks are pulled over at a higher rate despite the fact that police are biased against pulling them over? The answer is, of course, a difference in rate of driving violations, on average, between white and black drivers—a possibility which is highly likely if driving violations are related to socioeconomic status, as many other kinds of violations are.
Similarly, a higher rate of searches and citations does not suggest police bias, because we don't know the average rate at which police have legitimate reason to perform a search or give a citation for each of the black, white and hispanic driving populations. Indeed, we have strong reasons to suspect that, on average, police will have legitimate reasons to perform a search or give a citation more often for black drivers than white drivers—again, reflecting how rates of various types of infractions are highly related to socioeconomic status.
One way to investigate whether police initiate a search with less cause for one group than another is to examine how often police searches turn up contraband, or the "hit rate" of searches. If searches rarely turn up contraband for one group, but frequently do for another group, that suggests that police might be using a lower threshold of suspicion for initiating a search for the former, and higher threshold for the latter. Past investigations show that the hit rates tend to be similar for whites and blacks, suggesting an absence of bias, though they are much lower for Asians. If the hit rate approach is valid, this suggests that police might be more suspicious of Asians. But, it could also simply be that Asians are less likely to be carrying contraband even when exhibiting the exact same behaviors that are probable cause for search of other groups. For that reason, simple disparities like this actually tell us almost nothing about the presence or absence of discrimination.
Nevertheless, the headline of the Boston Globe article claims “report on Mass. traffic stops shows stubborn racial biases persist in policing”. The rest of the article strongly emphasizes the difference in search and arrest rates, and quotes extensively from “community leaders” and so called “experts” claiming the big takeaway from the study was police bias. One supposed expert,
Daniel Medwed, a law and criminal justice professor at Northeastern University, said “the key finding is that drivers of color are more likely to be searched and given citations after a stop.” That, he said, is “revealing about potential police biases in making judgment calls about whether a search is warranted or a citation merited under the circumstances.”
The Globe also quotes a community organizer lamenting that “it doesn’t seem like there’s any systemic change that’s happening to stop it,” then spends a couple paragraphs falsely implying that police stops are more dangerous for black people, and continues on to quote various other community activists making similar points.
In other words, despite a clear finding in the report that police are biased against pulling over black drivers, and a clear warning in the report that the difference in search and citation rates "doesn’t mean that the race/ethnicity of the stopped driver is the CAUSE of the search”, the Boston Globe intentionally framed the story to give the false impression that the report did find bias against blacks.
It did not. It literally found the opposite.
It’s worth taking a minute to pause and consider exactly how divisive and inflammatory this sort of dishonest spin actually is. It comes at a time when activists are spreading the lie that police are hunting and exterminating black citizens and when suspicion and resentment towards police within black communities is so high that activists are calling for abolition of police even while nearly 10,000 blacks per year are murdered by criminals across the country. It’s hard to imagine how the Globe could spin a report—that actually found discrimination in favor of black drivers—in a way that was any more poisonous to healing the fractured relationship between black communities and police officers.
False implications of discrimination are often far more damaging to disadvantaged groups than they are to the accused. And yet, people worried about the welfare of those groups frequently make such allegations without careful analysis of the facts.
So let's return to the question of who actually suffers from this intentionally inflammatory and divisive reporting and from the racially unequal application of the law it encourages. The answer to that question depends on who benefits most from careful, law abiding, driving. Good driving helps to protect the safety of the driver and the communities they are driving through. Bias against applying laws that encourage safe driving to black drivers, who are more likely to be driving through predominantly black neighborhoods, disproportionately hurts those black communities and black drivers.
Why would the Boston Globe intentionally frame a story in a false light that misleads people about police bias and encourages policies that plainly hurt black communities? That’s the question we should all be asking ourselves.
I sometimes worry that the spin of (selective) correlation=causation promoted by progressives causes African Americans to expect and to perceive racism excessively, essentially creating a self-fulfilling prophecy. Hard to know with certainty.
As you so often point, out applying the most logical base rate is vital to attempts to use statistics to evaluate claims of racism. To that end, has the 'veil of darkness' effect been validated in some other way? Merely because it makes sense doesn't make it true.
Thanks, Zac. I wish other journalists would address the question to the paper's managers/owners.... why ignore the facts? I think they owe their subscribers an answer.