Data that tells the truth. Conclusions that don't.

Statistical illusions are not exotic. They decide drug approvals, court verdicts, league tables, hiring rounds and headlines — and they survive because each is built from numbers that are individually, checkably true. The lie lives in the step from number to conclusion.

The collection is organised by mechanism rather than by field, because the same trap resurfaces everywhere wearing different clothes: an illusion of aggregation looks the same in a hospital and a ballpark. Each published entry opens with an interactive figure where the illusion happens in front of you — one toggle, two honest readings. Throughout, the colour claret marks the misleading reading, and each entry closes with the one question that would have saved you, collected at the bottom of this page as a pocket checklist. New entries are added as they're written; the dashed cards are next in the queue.

Each published entry is disarmed by a single question, asked before believing the number. The checklist grows with the compendium — memorise it and you can skip the rest of the site, though you'd miss the salmon.