Calculated Risks

To get yourself in the right frame of mind before reading this book, try watching a few optical illusion videos. There is no reason to think our visual cortex is any dumber than the rest of the brain — in fact, quite the opposite. That our inference can be so easily fooled in a domain which is supposedly our strong suit is humbling.

Our statistical inference is even worse, so a short book or two on statistical numeracy should be in everyone’s library. Gerd Gigerenzer’s Calculated Risks can be that book for most people. The assumption, easily defensible, is that “most people” will get more use out of understanding frequentist rather than Bayesian probability. After all, most probabilities people are bombarded with — your chance of dying from breast cancer with and without screening, the chance of your neighbor being the killer given a positive DNA match (you know, the day-to-day stuff) — is frequentist.¹

The only reservation to wholeheartedly recommending Calculated Risks to everyone is that it falls into the category of “blog post books”, if you believe that most non-fiction books should, in fact, have been just blog posts. Or, since blogs are out of vogue, a 15-minute YouTube video may do. Or perhaps a single sentence: use natural instead of relative frequencies (e.g. 1 in 10.000 instead of 0.01%). Let your faulty cortex fill in the rest.