What does it mean to talk about the risk of, say, being in an airplane crash or being struck by lightning? Calculations of risks are averages, so they have limited value to the individual. Airplanes, for instance, may be safe in terms of deaths per passenger mile, but that says little about the flight you’re about to board--one that entails several takeoffs and landings in bad weather, on a day following a night when the pilot may have had a few too many. To state a risk implies a foretelling, but this predictive power is misleading. Risk calculations almost always use historical data and mask the dubious assumption that the future will behave like the past.
With these caveats in mind, we combed the statistics of risky behavior to come up with a few numbers to ponder. In many cases, we had to knead the data into the format of ...
