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June 14, 2011

Bayesian Truth Serum


Just a teaser, the headline up top is part of the title of MIT professor Drazen Prelec's October 15, 2004 Science Magazine paper entitled "A Bayesian Truth Serum for Subjective Data"; the abstract follows.

Subjective judgments, an essential information source for science and policy, are problematic because there are no public criteria for assessing judgmental truthfulness. I present a scoring method for eliciting truthful subjective data in situations where objective truth is unknowable. The method assigns high scores not to the most common answers but to the answers that are more common than collectively predicted, with predictions drawn from the same population. This simple adjustment in the scoring criterion removes all bias in favor of consensus: Truthful answers maximize expected score even for respondents who believe that their answer represents a minority view.

Economist Tyler Cowen, in his book "Discover Your Inner Economist," noted that the techniques described in Prelec's paper can be used to indirectly get a person's real opinion about something by asking the individual what she thinks everyone else believes.

Wrote Cowen, "The premise behind this approach is the following. If people truly hold a particular belief, they are more likely to think that others agree or have had similar experiences."

He continued, "When we talk about other people, we are often talking about ourselves, whether we know it or not."

June 14, 2011 at 04:01 PM | Permalink


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What about those of us that prefer to be around others that how opposing thoughts and beliefs? I find snobby liberal overprivileged pretentious white liberals to be boring...and yet, I am probably the biggest I know. I'd rather hang out with people that aren't anything like me...

Posted by: clifyt | Jun 15, 2011 8:41:53 AM

And we humans also have a very real tendency to spend our time with other people who share our opinions and beliefs, reinforcing this kind of response.

Posted by: Annick | Jun 15, 2011 3:21:02 AM

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