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The "Machine Bias" report that ProPublica published about the Northpointe software (and that is cited in OP) has been shown to be wrong. Source: Flores, Bechtel, Lowencamp; Federal Probation Journal, September 2016, "False Positives, False Negatives, and False Analyses: A Rejoinder to “Machine Bias: There’s Software Used Across the Country to Predict Future Criminals. And it’s Biased Against Blacks.”", URL http://www.uscourts.gov/statistics-reports/publications/fede... In fact the ProPublica analysis was so poorly done that the authors of the above study wrote in the conclusion: > "It is noteworthy that the ProPublica code of ethics advises investigative journalists that "when in doubt, ask" numerous times. We feel that Larson et al.'s (2016) omissions and mistakes could have been avoided had they just asked. Perhaps they might have even asked...a criminologist? We certainly respect the mission of ProPublica, which is to "practice and promote investigative journalism in the public interest." However, we also feel that the journalists at ProPublica strayed from their own code of ethics in that they did not present the facts accurately, their presentation of the existing literature was incomplete, and they failed to "ask." While we aren’t inferring that they had an agenda in writing their story, we believe that they are better equipped to report the research news, rather than attempt to make the research news." What I find remarkable is that in the ongoing coverage ProPublica has published on this subject in December 2016 they interviewed a bunch of more people, but none of the folks that have criticized their analysis (published in September). Make of that what you will. |
I don't want to end up defending the methods ProPublica have used as I am certainly not qualified to do that and have no skin in this game anyway. I posted here initially in response to a very general question about bias in models, and I'd rather not be drawn into a lengthy discussion about this specific piece.
However, I do have one or two issues with the conclusions you seem to be drawing in your comment:
> What I find remarkable is that in the ongoing coverage ProPublica has published on this subject in December 2016 they interviewed a bunch of more people, but none of the folks that have criticized their analysis (published in September). Make of that what you will
I'm not sure it's possible to conclude anything from that actually. There could be plenty of non-nefarious reasons for the omission. For instance, one individual they cite in the follow up review [1] has written a paper citing the paper you linked to showing that "the differences in false positive and false negative rates cited as evidence of racial bias in the ProPublica article are a direct consequence of applying an instrument that is free from predictive bias to a population in which recidivism prevalence differs across groups". [2] The Flores et al paper seems to claim that showing that predictive bias does not exist is enough, which it would seem is not the case. If racial bias might appear anyway in the situations in which the model is often applied in reality, then perhaps the ProPublica authors felt that the paper cited below [2] adequately addressed the criticism of the paper you cited and decided not to reference the FPJ article for reasons of clarity in their follow up? I think discounting their work because of a single omission would be throwing the baby out with the bathwater.
The ProPublica authors cite plenty of other research in the area in their follow ups. Sure, this is all largely in agreement with their conclusions or go further, but does this matter unless those publications are incorrect? The ProPublica authors are writing for a news publication not an academic journal and are therefore not obligated to cite every relevant publication when they're publishing. So long as they can do this without forcing a conclusion then I don't see the problem. Perhaps they deliberately ignored the paper. Who knows?
[1] https://www.propublica.org/article/bias-in-criminal-risk-sco...
[2] https://arxiv.org/abs/1610.07524