Availability Misweighing
We overweight information that's recent, vivid, or easily recalled.
Key Principle
Seek base rates and historical data, not just recent or vivid examples.
Understanding Availability Misweighing
The availability heuristic causes us to judge probability based on how easily examples come to mind. Recent events, vivid stories, and dramatic occurrences are easily recalled, so we overestimate their frequency.
After a plane crash makes headlines, people overestimate the danger of flying—even though driving to the airport is statistically more dangerous. After a friend's startup succeeds, we overestimate our own chances—forgetting the dozens of failures we never heard about.
This bias is exploited by media (dramatic stories get attention), marketers (vivid testimonials), and our own minds (recent experiences feel more relevant).
Real-World Examples
- Overestimating crime rates after watching news coverage.
- Overconfidence in a strategy because of a recent success.
- Fear of rare events (terrorism, shark attacks) that get media coverage.
- Hiring based on a memorable interview moment rather than overall qualifications.
How to Apply This
Always ask: What's the base rate? How often does this actually happen?
Seek data, not anecdotes, for important decisions
Be suspicious of decisions driven by recent events
Keep records to counteract selective memory
Common Mistakes to Avoid
- Making decisions based on recent anecdotes rather than data
- Overreacting to vivid but rare events
- Underweighting boring but important information
- Letting media coverage distort your risk assessment
Notable Quotes
"The world is not driven by greed. It's driven by envy."
— Charlie Munger