Oscar_Cunningham comments on Open Thread, September 15-30, 2012 - Less Wrong

7 Post author: OpenThreadGuy 15 September 2012 04:41AM

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Comment author: NancyLebovitz 24 September 2012 03:08:01PM *  2 points [-]

Movement toward taking a statistical approach to the quality of evidence from fingerprint similarity

Before you read that article, what was your opinion of fingerprint evidence?

My first exposure to the idea that fingerprint evidence might not be all that good was in L. Neil Smith's The Probability Broach, in which the viewpoint character, a policeman, wonders whether all fingerprints really are unique, and also wonders whether the government might disappear people who had identical fingerprints.

(Surprisingly to me, the Salon article mentions that identical snowflakes have been found.)

My second exposure was an article in Lingua Franca, which brought up the more plausible issue that fingerprints from crime scenes are likely to be partial and/or fuzzy.

Submitting...

Comment author: Oscar_Cunningham 24 September 2012 05:13:29PM 0 points [-]

The article doesn't actually contain any data saying that fingerprints are reliable. If I had to guess, I'd say that a (non-partial) fingerprint match had an odds ratio of around 10^7, a hefty 22 bits of info. Is there any data to contradict that? Or is this just the "but there's still a chance, right?" fallacy?