Another researcher conducted one of the largest and longest running studies of the performance of experts at predictions. Philip Tetlock tracked the forecasts of 284 experts in many topics over a 20-year period. In total, he had gathered more than 82,000 individual forecasts covering elections, wars, economics, and more. Tetlock summarized these findings in his book Expert Political Judgment: How Good Is It? How Can We Know?13 His conclusion was perhaps even more strongly worded than Meehl’s:
