A moviegoing colleague writes:
I just watched the movie Zero Dark Thirty about the hunt for Osama Bin Laden. What struck me about it was: (1) Bayes theorem underlies the whole movie; (2) CIA top brass do not know Bayes theorem (at least as portrayed in the movie).
Obviously one does not need to know physics to play billiards, but it helps with the reasoning.
Essentially, at some point the key CIA agent locates what she strongly believes is OBL’s hidding place in Pakistan. Then it takes the White House some 150 days to make the decision to attack the compound. Why so long? And why, even on the eve of the operation, were senior brass only some 60% OBL was there?
Fear of false positives is the answer. After all, the compound could belong to a drug lord, or some other terrorist. Here is the math:
There are two possibilities, according to the movie…