Friday, May 13, 2011

Associated Content: "The Misuse of PolitiFact's Rankings"

Anonymous contributor "Thales" of Yahoo's Associated Content provides us yet another reminder of how PolitiFact's collected ratings are pretty much useless without a check on selection bias:
There's no way they could cover every political statement made by even a couple politicians, let alone dozens of them. But if PolitiFact hasn't given a comprehensive evaluation of all of the statements of these politicians -- or at least equally representative samples from each of them -- then how can they be used to rank these people in terms of veracity or ignorance? They can't.
Thales also notes PolitiFact's tacit approval of the misuse of its rankings:
PolitiFact has said nothing about this use -- I would argue, misuse -- by The Daily Beast of their Truth-O-Meter rankings. Although The Daily Beast is accurately reporting PolitiFact's evaluations, they're doing it in a way that leads to false (or at least questionable) implications. This kind of situation -- accurate statement with questionable implication -- has been variously rated by PolitiFact in the past as being anywhere from "True" to "Half True" (again, they're inconsistent in these rankings). But, to date, PolitiFact and the Truth-O-Meter remain silent on The Daily Beast's "10 Most Ignorant Politicians" list.
As to Thales' first point, PolitiFact would not need to rate every political statement in order to negate selection bias if the selection process were random.  But that process is not random, unless we disbelieve PolitiFact's description.

And to amplify Thales' second point, PolitiFact can hardly scold the Daily Beast for its misuse of the data without undercutting its own practice of directing readers to judge individuals according to their Truth-O-Meter "report card":
(W)e thought it would be timely to look at Beck's record on the Truth-O-Meter. As you can see from the running tally in his PolitiFact file, we've rated 17 statements by the Fox News talk show host. It's fair to say that record skews toward the False end of the Truth-O-Meter.
Yes, and?

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