Philip Tetlock has done one of the most comprehensive studies of forecasters, their accuracy, and their excuses. When studying experts’ views on a wide range of world political events over a decade, he found that, across the vast array of predictions, experts who reported they had 80 percent or more confidence in their predictions were actually correct only around 45 percent of the time. Across all predictors, the experts were little better than coin tossers.
Every day, experts bombard us with predictions, but how reliable are they? Until a few years ago, no one bothered to check. Then along came Philip Tetlock. Over a period of ten years, he evaluated 28,361 predictions from 284 self-appointed professionals. The result: in terms of accuracy, the experts fared only marginally better than a random forecast generator. Ironically, the media darlings were among the poorest performers; and of those the worst were the prophets of doom and disintegration. Examples of their far-fetched forecasts included the collapse of Canada, Nigeria, China, India, Indonesia, South Africa, Belgium and the E.U. None of these countries has imploded.
‘There are two kinds of forecasters: those who don’t know, and those who don’t know they don’t know,’ wrote Harvard economist J.K.Galbraith.
Excerpt from: The Art of Thinking Clearly by Rolf Dobelli