The rules
Knowledge pays. Overconfidence costs.
01
Read the statement
Every UTC day opens a new market of ten factual statements, the same for every trader.
02
Name your probability
Slide to how likely you think it is to be true. 100% is certain, 0% is certainly false, 50% means you've no idea.
03
Put credits behind it
Invest 25, 50, 100 or 250 credits. The answer, the explanation and the source appear the moment your position settles.
The scoring rule
Your profit or loss on a statement is
profit = round(stake × (0.25 − (p − outcome)²))
where p is your probability that it's true (0 to 1) and outcome is 1 if it's true and 0 if it's false. This is a quadratic scoring rule, the same idea weather forecasters are judged by: the best strategy is always to report what you actually believe.
With 100 credits invested
| Your call | Answer | Result |
|---|---|---|
| 100% TRUE | TRUE | +25.00 |
| 80% TRUE | TRUE | +21.00 |
| 50% TRUE | TRUE | 0.00 |
| 80% TRUE | FALSE | −39.00 |
| 100% TRUE | FALSE | −75.00 |
Being right at 100% earns a quarter of your stake, but being wrong at 100% costs three quarters of it. A 50/50 call can neither win nor lose. So when you're unsure, say so.
Fair play
- Everything is settled on the server. Answers stay there until your position on that statement is final.
- A settled position can't be changed or submitted twice, and your progress is saved after every trade, so you can leave and pick up where you were.
- Your balance carries over from day to day. If you ever drop below 25 credits, the next day opens with fresh capital of 1,000.
- Credits are play money. Fact Market involves no real money and no gambling.