Suppose: Calibration Training

You don't just say true or false. You say how sure you are.

Every day we make decisions on the back of estimates and best guesses. The estimate caps the quality of the decision, and almost no one ever trains the estimate. Most people are quietly overconfident. Suppose shows you by how much.

SEE YOUR BLIND SPOTS Most of us round probabilities to yes or no. A 30% chance gets heard as "that won't happen," and when it happens anyway, the forecast gets called wrong. The useful range is the middle, and it's the part nobody practices: the real difference between being 60% sure, 80% sure, and 99% sure. Suppose trains that difference, then shows you where yours breaks down.

HOW IT WORKS You're presented with a true/false claim. Rather than picking an answer, you move one slider to say how likely the claim is to be true: 1-99%, or 50% if you genuinely have no idea. Lock it in and you immediately see whether it was true, the fact behind it, and what you scored. Points come from the Brier score, the standard measure for probabilistic forecasts. The math is built so that overstating your confidence costs you more than it can ever win, which makes reporting what you actually believe the highest-scoring strategy. A coin flip earns zero. Confident and wrong is the worst answer on the board.

TWO WAYS TO TRAIN • True/false: estimate how likely a claim is to be true on a single slider, from 1 to 99. • Estimation (Pro): given a level of confidence, give the range you'd put a number in, and see where the truth actually falls. Scored with a Winkler interval score, so tight, well-centered ranges beat wide, safe ones.

SEE YOUR PROGRESS Feedback lands on every answer, and your profile keeps the long view: a lifetime calibration curve against the line of perfect calibration, so you can see the shape of your own bias. Plus accuracy by category, your Brier score over time, an activity heatmap, and a streak.

THOUSANDS OF QUESTIONS Calibrate your judgment across thousands of verified questions spanning world & geography, science & nature, history, sports, arts & culture, technology, and business & economics. Every claim carries a checked answer and a short explanation of what's actually true. Difficulty is spread on purpose, so you're not answering easy questions at 95% forever.

NOT JUST TRIVIA Trivia enthusiasts have plenty here, but Suppose takes it a step further: the interesting questions become the half-remembered ones, where you're somewhere between a guess and a certainty. Standard trivia throws that away and scores you right or wrong. Suppose keeps it. A lucky guess and a solid recall both count, and they don't count the same.

TRAIN FASTER WITH PRO Free users get a daily set, forever. Pro unlocks: • Unlimited true/false: sets of 10, 20, 50, or endless • Access to Estimation mode: answer in numeric ranges across thousands more unique questions • Access to all categories, and choose which ones you train on Pro is available as an annual subscription or one-time lifetime purchase.

No ads, ever. Works signed out, with no account required. Optional sign-in to preserve your progress across devices.

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