FallacyExtension Neglect · Entry 41
Base Rate Fallacy – when you ignore general statistics for a specific case
Do you trust vivid examples more than dry statistics? That’s Base Rate Fallacy – when general probabilities are ignored in favor of specific cases, even when statistics provide a more accurate prediction.
Where it can show up
- Medicine – a test for a rare disease comes back positive, and you panic, forgetting that false positives are more common than the disease itself.
- Business – you hear about a startup that became a billion-dollar company and assume you have the same odds, ignoring failure rates.
- Crime – you think forensic evidence is conclusive, without considering how often similar evidence appears among innocent people.
A practical countermeasure
- Look at overall numbers, not just stories – rare cases stand out, but they don’t represent the real probability.
- Consider the full probability – even if a test is ‘90% accurate,’ what matters is how common the condition actually is.
- Be wary of success stories – one inspiring exception doesn’t erase thousands of unseen failures.
