How To Spot A Misleading Statistic: Twitter?s Curious Political Ad Study

Statistics are everywhere these days, and it's difficult to know which ones to take seriously. Occasionally, a "report" comes out that's so misleading it presents a teachable moment on how to spot a bad statistic. Last week, Twitter made headlines for claims that users who are exposed to their political advertisements, in the form of promoted tweets, are about twice as likely to visit a campaign donation page than the "average" Internet user. However, Twitter users are also more likely to be from a educated voting demographic and, more importantly, prior research on these kinds of non-randomized advertising campaigns show that the results can be exaggerated by as much as 2000%. Moreover, using percentages, rather than actual numbers, is a well-known technique in disguising poor results (i.e. if only 1 in a million users normally visit a website, and the ad gets one more person to visit, its "doubled" the visitors).

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