The old joke about the statistician who drowned in a lake with an average depth of one foot is a reminder that while the mathematics of probability theory are rock solid (er, within a certain range of error), the questions that the numbers attempt to illuminate are a bit more slippery. To put this in another way, a statistic is only as valid as the manner in which the question it tries to answer is framed. And there’s the rub: a question can be spun in such a way that the answer will confirm any sophistry.
This insight was recently brought home to me by Tyler Cowen’s wonderful Discover Your Inner Economist: Use Incentives to Fall in Love, Survive Your Next Meeting and Motivate Your Dentist. But even libertarian economists can fall prey to their inner biases. (I haven’t discovered whether Cowen calls himself a libertarian or not, but following Rush Limbaugh’s opinion that all economists worth their salt are libertarian, I suspect he is.)
At one point, Cowen briefly discusses fear of flying, citing various statistics that “prove” that flying is, hands down, much safer than driving a car. When one compares mortality rates per mile traveled and per passengers involved, the conventional figures decisively prove their point.
So why am I not scared of driving? As Ayn Rand famously stated, “Check your premises!”
Having taken flying lessons (and having had to land a single-engine plane that lost power), I have a slightly different take on the matter. A Cessna 150 with a perfectly centered dead engine practically lands itself, slowly gliding down at the proper angle, needing only a steady hand to keep it from diving into a stall. By comparison, a multi-engine jet with the reduced glide ratio that results from swept-back wings, and the out-of-balance weight and thrust from an off-center, suddenly faulty engine, almost requires a miracle to land safely.
Cowen, along with many others, believes that fear of flying is irrational. Now, I consider myself a rational empiricist, but when facing a flight, I gird my loins and make sure my affairs are in order. And I don’t think my fear is irrational. Yet I had never really tried to work out the problem until I read Tyler Cowen, who skewers popular fallacies as only a libertarian economist can. My conclusion is that he may have embraced a popular fallacy himself.
A stalled car engine is an inconvenience for, perhaps, half a dozen people at the most, while a stalled jet engine is a likely death sentence for hundreds of passengers. Having a pigeon fly into a car’s grille is startling, but it has far from the same consequences as having a pigeon fly into the cowling of a Rolls-Royce Trent 900 engine.
The questions I would pose to determine the safety of flying vs. driving would be: What percentage of mechanical malfunctions in cars result in fatalities? And how many fatalities? But what percentage in planes? I’m willing to bet that mechanical malfunctions (or operator errors) in an airplane cause way more fatalities than the same problems in a car. Different premise, different conclusion.