know what you know
Welcome to Guessum, a game created in 2010 by Sharad Goel, Dan Goldstein, and Daniel Reeves (with thanks to Sergii Kalinchuk for help resurrecting it in 2017) that helps you learn to make better predictions. Log in via Facebook to start playing.
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How it works

You are paired with a randomly selected partner with whom you compete to answer a series of 10 trivia questions. For each question—for example, What was Martin Luther King, Jr.'s age at death?—you have 60 seconds to specify an interval of numbers (e.g., 30 - 45) that you believe contains the true answer. Each question is worth 100 points for which you and your partner are vying. The smaller your interval, the more points you get—but you're penalized if your interval doesn't contain the actual answer.

In each round you're asked either for an interval that you are “50% sure” contains the correct answer, or for one that you are “90% sure” contains the correct answer. The greater your degree of certainty, the more you are penalized for missing the answer. So, it's worse to miss the answer when you are “90% sure” than when you are “50% sure”.

After you answer the trivia questions, we'll ask you to make a prediction about some future event. Come back in a few months to see how well you've learned to predict the future!

Important

When you are “90% sure” that your interval contains the correct answer, you should expect to get the question right 9 out of 10 times. Likewise, when you are “50% sure”, your interval should contain the answer 5 out of 10 times. Your actual hit rate is shown next to each question, and you should use that information to help adjust the size of your intervals. For example, if your 50% intervals typically contain the true answer only 2 out of 10 times, then they are too narrow and you should widen them; and if they typically contain the true answer 8 out of 10 times, then they are too wide and you should narrow them.

PS, no googling!

All-Time High Scorers
 1. michael s. 847 2. adom h. 828 3. laurent b. 812 4. anthony m. 809 5. norman p. 797 6. michael s. 773 7. patrick b. 770 8. aviad r. 765 9. michael s. 764 10. laurent b. 764 11. michael s. 763 12. daniel r. 757 13. maximilian n. 751 14. elissa f. 751 15. andres r. 746 16. norman p. 743 17. elissa f. 738 18. anthony m. 736 19. chelsea v. 735 20. adom h. 731 21. patrick b. 713 22. elissa f. 707 23. nicholas r. 704 24. norman p. 697 25. daniel r. 696 26. richard p. 695 27. maximilian n. 694 28. julia w. 694 29. elissa f. 693 30. daniel r. 688 31. elissa f. 688 32. daniel r. 684 33. andres r. 683 34. stÃ©phanie t. 682 35. leonie k. 682 36. elissa f. 682 37. stÃ©phanie t. 682 38. daniel r. 681 39. michael s. 679 40. glenn d. 679 41. dan g. 679 42. delen h. 677 43. stÃ©phanie t. 674 44. michael s. 673 45. laurent b. 673 46. elissa f. 659 47. laurent b. 657 48. elissa f. 656 49. patrick b. 656 50. adom h. 651