If, after watching months of hysterical TV coverage of H1N1, or swine flu, you think you already know everything you need to know, you are probably wrong. Pandemic influenza is notoriously complex and it changes all the time. The best defense is wisdom. But because of the way our brains are wired, we tend to overestimate how well we understand the risks. Check your own IQ (influenza quotient) with our nifty Pandemic Pop Quiz.