Superforecasting: The Art and Science of Prediction

by Philip E. Tetlock

Of course if Doug Lorch were a uniquely gifted oracle, he would pose little threat to the status quo. There is only so much forecasting one man can do. But Doug isn’t unique. We have already met Bill Flack, the retired Department of Agriculture employee from Nebraska. There were 58 others among the 2,800 volunteers who scored at the top of the charts in year 1. They were our first class of superforecasters. At the end of year 1, their collective Brier score was 0.25, compared with 0.37 for all the other forecasters—and that gap grew in later years so that by the end of the four-year tournament, superforecasters had outperformed regulars by over 60%. Another gauge of how good superforecasters were is how much further they could see into the future. Across all four years of the tournament, superforecasters looking out three hundred days were more accurate than regular forecasters looking out one hundred days. In other words, regular forecasters needed to triple their foresight to see as far as superforecasters.