Choose the urn before you draw.
Ellsberg used urn choices to study ambiguity: a decision maker may treat unknown probabilities differently from known ones.
Inside this model
The known urn is 50% red. For the unknown urn, a red share is drawn once per session uniformly from [50−width/2, 50+width/2] percent; its value stays hidden until you play. Each urn pays 10 on red, 0 otherwise. The chart shows payoff under every possible unknown composition, not a claim about your preferences.
Out in the world
A practical use
Compare a contract with known failure odds with one whose probability cannot be estimated confidently from available data.
A useful lens. Not a universal law.
- The random composition is a teaching device. Ellsberg's point concerns unknown beliefs and preference patterns, not a known uniform distribution over urn compositions.
Associated thinkers
Further reading
Explore the original research or the teaching reference behind this experiment.
Daniel Ellsberg — Risk, Ambiguity, and the Savage Axioms ↗