Ask the base rate before evaluating the specific case

Before judging any individual instance, first establish how often this kind of thing happens in general.

Why it works

Base-rate neglect happens because specific, vivid information is processed automatically and effortlessly, while base rates require deliberate retrieval and computation. The automatic processing of the specific story crowds out the base-rate lookup — it simply does not occur. Placing the base-rate question first in your decision protocol forces the prior probability into working memory before the vivid case can dominate.

How to do it

1. Before evaluating any specific case, write or say: "In general, how often does this kind of thing succeed/happen/fail?"
2. Look up the reference class rate if you can; estimate it if you can’t.
3. Anchor your probability estimate on that number before adding anything from the specific case.

Evidence

Kahneman and Tversky’s original "engineer vs lawyer" studies demonstrated base-rate neglect directly: subjects ignored stated base rates when given personality descriptions. The effect has been replicated extensively across domains. (observational)

Sources

• Kahneman & Tversky (1973), "On the Psychology of Prediction," Psychological Review

Common mistake

Asking for the base rate only after you’ve already formed a strong impression from the specific case — at that point the anchor is already set and the base rate gets rationalized rather than weighted.