Give a 90%-sure range for a handful of facts, then see how often the truth actually landed inside. Almost nobody hits 90% — most of us are quietly, confidently overconfident.
Interactive — the calibration gamegive a 90%-sure range
This isn't a trivia quiz. For each fact, give a low–high range wide enough that you're 90% sure the real answer sits inside it. Not sure when the iPhone launched? “2000 to 2015” is a fine answer — the skill is knowing how wide to go.
Then see how many of your eight ranges caught the truth. If you're really 90% sure each time, you'd catch about seven of eight. Most people catch far fewer — their ranges are too narrow. That gap is overconfidence, and noticing it is the point.
- The first iPhone went on sale in…–
- Mount Everest is how many meters tall?–m
- An adult human body has how many bones?–
- The Berlin Wall fell in…–
- How many countries are in the European Union?–
- A marathon is how many kilometers?–km
- Light travels how many kilometers per second?–km/s
- Wikipedia launched in…–
fill all eight ranges — 0/8 done