Must-Read: Mark Thoma sends us to Rajiv Sethi, who makes a convincing case that the very sharp Sendhil Mullainathan has gotten one wrong here:
: Threats Perceived When There Are None: “He argues that ‘eliminating the biases of all police officers would do little…
…to materially reduce the total number of African-American killings…. 28.9 percent of arrestees were African-American… not very different from the 31.8 percent of police-shooting victims…. If police discrimination were a big factor in the actual killings, we would have expected a larger gap between the arrest rate and the police-killing rate….
A key assumption… is that encounters involving genuine (as opposed to perceived) threats to officer safety arise with equal frequency across groups…. A safe encounter might well be perceived as risky, as the following example of a traffic stop for a seat belt violation in South Carolina…. Sendhil is implicitly assuming that a white motorist who behaved in exactly the same manner as Levar Jones did in the above video would have been treated in… the same manner by the officer…. Think of the encounter involving Henry Louis Gates and Officer James Crowley back in 2009… a safe encounter… [that] may not have happened in the first place had Gates been white. If the very high incidence of encounters between police and black men is due… to encounters that ought not to have… a disproportionate share… will be safe, and one ought to expect fewer killings per encounter in the [presence of bias toward having an encounter and the] absence of bias [once the encounter begins]. Observing parity would then be suggestive of bias…. In justifying the termination of the officer in the video above, the director of the South Carolina Department of Public Safety stated that he ‘reacted to a perceived threat where there was none.’ Fear is a powerful motivator… even when there are strong incentives not to shoot…