On Facebook's “Ethnic Affinities” ad targeting: thoughful tweet essay from J. Nathan Matias, MIT

Matias is a Phd student, MIT Media Lab / CivicMIT, also affiliated with Berkman Klein Center, Harvard.

ProPublica article about Facebook ad-targeting program including “Ethnic Affinities” option letting advertisers target or exclude users by their automatically characterized affinity:

Facebook Lets Advertisers Exclude Users by Race