In All Probability

As a teenager, I had the good fortune to meet Tom K├Ârner. He had written a book, The Pleasures of Counting, that opens with a story about John Snow.

Snow was a 19th century English physician who painstakingly collected and analyzed vast amounts of data to convincingly argue that cholera spreads through contaminated drinking water, and not, as was once widely believed, from some kind of air pollution.

This struck me as a powerful example of how mathematics, and in particular, statistics, can impact our lives. How many more would have succumbed, had the true cause remained hidden?

Yet today, probability and statistics seem much maligned. Statistics are worse than “damned lies”; they’re “pliable”; one can “prove anything by statistcs except the truth”; they are the means to produce “unreliable facts from reliable figures”.

How did this happen? I’m sure these famous quotes were composed mainly in jest, and perhaps referred to shady accounting more than actual calculation. But these days, even the mathematics itself seems suspect:

Statistics is indeed a troubled subject. It turns out some guy named R. A. Fisher is to blame. Fisher had a tragic combination of gifts and flaws that led to today’s erroneous orthodox statistics. (Despite an ever-growing mountain of evidence, Fisher steadfastly refused to believe smoking causes lung cancer. How good could his methods be?)

My undegrad introductory course on probability and statistics followed Fisher’s dogma. As a result, I felt that the methods they taught seemed like black magic more than mathematics. But I was convinced that the lecturer only seemed to be teaching superstitions because my understanding was too shallow, and I concluded I must have a poor intuition for the subject.

Years later, and determined to conquer my weakness in this area, I went back to my textbook. And some other books. I discovered the shocking truth: my undergrad textbook is wrong. For once, a crazy conspiracy theory was true and They really were corrupting us all with Their false mathematics.