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. laurent b. 764
10. michael s. 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. elissa f. 688
31. daniel r. 688
32. daniel r. 684
33. andres r. 683
34. stéphanie t. 682
35. leonie k. 682
36. elissa f. 682
37. stéphanie t. 682
38. michael s. 679
39. glenn d. 679
40. dan g. 679
41. delen h. 677
42. stéphanie t. 674
43. laurent b. 673
44. michael s. 673
45. elissa f. 659
46. laurent b. 657
47. patrick b. 656
48. elissa f. 656
49. laurent b. 651
50. adom h. 651