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Decision MakingMember ingredient
Category Size Bias
A proposed probability error in which an individual outcome seems more likely when it sits inside a larger category—but later high-powered studies suggest much of the effect came from confusing instructions.
Public evidence overview
One checked source, with its limits.
This preview is not the complete evidence base. Use it as a question to investigate in your own product, not as a prediction of what an individual will do.
Checked source previewAcademic paper
The Category Size Bias: A Mere Misunderstanding
Research-assisted source review
- What it supports
- Three of five original effects could be reproduced, but clearer wording reduced or eliminated them, one study reversed the effect and the authors concluded that the other two original findings were false positives.
- Where it may not transfer
- The paper is a strong direct challenge rather than a final proof that no category framing effect can ever occur. Some residual patterns and task variations remain, and probability judgments outside these experimental formats may have different information structures.
See how sources and limitations are checked in our editorial method.
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