And, indeed: it was. While the audience for the neutral ad was nearly evenly split, the researchers found that, on average, “Facebook delivers our ads with content from Democratic campaigns to over 65% users registered as Democrats, while delivering ads from Republican campaigns to under 40% users registered as Democrats, despite identical targeting parameters.” Targeting based on Facebook’s classification of users’ political leaning, instead of party registration, led to even more skewed results. Just as important, it cost much more to reach users across the political divide. For example, the study found that it cost 50 percent more to get a conservative voter to see Sanders content than Trump content.
“In traditional television or newspaper advertising, two political campaigns that have the same financial resources have an equal chance to reach the same audiences,” said Aleksandra Korolova, a computer scientist at USC and one of the study’s authors. “Whereas what we’ve showed in this work is that Facebook will charge the political campaigns differently depending on who they are and will deliver the ads to a subset of the users that they’re targeting according to what Facebook thinks is important—not according to what the political campaign may be trying to do.”
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Source: How Facebook’s Political Ad System Is Designed to Polarize | WIRED