Case file
Base Rate Fallacy
- Filed under
- Too Much Information
- Also recorded as
- Base rate neglect
The charge
We ignore general prevalence data and focus too much on case-specific details. That makes vivid anecdotes or individuating information crowd out the broader odds.
How it operates
Specific stories feel more diagnostic than abstract statistics, even when the statistics carry most of the predictive value. The mind prefers representative narratives over population rates.
Logged incidents
- Incident 01
A startup backs an unusually charismatic founder profile while ignoring the very low base rate of success in that category.
- Incident 02
A recruiter overweights one dazzling portfolio project and underweights the historical hiring signal from structured assessments.
- Incident 03
A fraud team treats a suspicious-looking transaction as likely fraud without considering how rare fraud actually is among similar transactions.
What to watch for
Ask yourself: 'What is the base rate for cases like this before I get seduced by the specifics?'
Recommended action
Use Bayesian updating or at least a simple reference-class forecast before judging an individual case. Base-rate training reliably improves probability estimates.
Known associates
- Halo EffectEasily confusedHalo effect is when one positive trait or first impression spills over into unrelated judgments about the…
- Availability HeuristicEasily confusedWe judge how likely or common something is by how easily examples come to mind, not by actual frequency.
- Attentional BiasWe selectively notice certain kinds of information while overlooking the rest, especially information tied to…
- Illusory Truth EffectRepeated statements start to feel true simply because they feel familiar.
- Mere-Exposure EffectWe tend to like things more after repeated exposure, even when the repetition provides no new value.
- Context EffectOur judgment of an option shifts depending on what other options or surrounding cues are present.
Source of record