Swedroe: Grading The Forecasters

July 28, 2017

  • Up to one month: 0.25
  • Up to three months: 0.50
  • Up to nine months: 0.75
  • Beyond nine months (up to two to three years): 1.00
  • If the forecast does not include a time frame, or unless there is an impression stating otherwise: 0.25

Following is a summary of the authors’ findings:

  • Across all forecasts, accuracy was 48%—worse than the proverbial flip of a coin.
  • Two-thirds of forecasters had accuracy scores below 50%.
  • About 40% of forecasters had an accuracy score between 40% and 50%.
  • About 3% of forecasters fell in the left tail, with accuracy scores below 20%.
  • About 6% of forecasters fell in the far right tail, with accuracy scores between 70% and 79%.
  • The highest accuracy score was 78% and the lowest was 17%.

The distribution of forecasting accuracy by the gurus examined in the study looks very much like the common bell curve—which is what you would expect from random outcomes. That makes it very difficult to tell if there is any skill present.

Famous Forecaster Scores
There were many well-known forecasters among the results. I’ve highlighted 10 of the more famous, most of whom I’m sure you’ll recognize, along with their forecasting score:

 

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