 The posterior probability that the defendant is the source, \(\Pr(\source\pmid \match)\) is roughly \(1-.83=.17\), much lower than the exaggerated value of .95. This posterior probability would have dropped even lower if the prior probability were lower. A similar analysis applies to the Collins case. If the prior probability of the Collins’s guilt is sufficiently low—say in 1 in 6 million—the posterior guilt probability given the match with the eyewitness description would be roughly .7, much less impressive than