Juries bad at judging guilt and innocence?
The answer is yes, according to Bruce Spencer, professor of statistics at Northwestern University. Spencer purports to arrive at the accuracy of jury verdicts (PDF link) by comparing the jury verdict to a judge’s opinion of the correct answer. Spencer then does a lot of fancy math and flings about some casual assumptions like juries rarely detect a judge’s opinion of the proper outcome and that judges are more accurate on average, all of which he claims indicate that juries render incorrect verdicts about 15% of the time.
This would seem to indicate that juries are bad decision-makers, although for the life of me, I can’t make heads or tails of the math Spencer uses to arrive at his conclusion, and I wish someone would translate it into English for me so I could make up my mind whether it is believable or not. On the one hand, it seems that statistical analysis might be able to predict such a thing. On the other, it doesn’t seem like Spencer worked hard enough to “statisticalize” all the variables. Which would seem to be nearly impossible, really.
