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A tool to practice overcoming “the mother of all biases”: overconfidence

Football teammates celebrate a goal.
Reuters/Amanda Perobelli
Overconfidence doesn’t just hurt individuals—it can drag down entire teams.
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For Quartz members only, here’s your chance to practice one of the biggest decision-making mistakes: overconfidence. (Psychologists Don Moore, of the University of California, Berkeley, and Max Bazerman of Harvard, call it “the mother of all biases” in their textbook on decision making.)

For each of the questions below, provide a numerical range with the bottom end below your best guess and the high end above your best guess. Your goal isn’t accuracy, it’s to set the ranges wide enough that the correct value falls into your range eight out of 10 times—but not so wide that all 10 answers are within your ranges. In other words, you want to set your ranges so the truth falls within them 80% of the time.

This version of the exercise has over 100 different items to estimate and will keep track of your progress from round to round.

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