Survivorship Bias
Type: Cognitive Bias
Local HTML: survivorship_bias.html
Definition
We only see the winners, not the losers who tried the same thing. The graveyard is invisible.
WWII example: Military studied planes that returned, wanted to armor where they were hit. Statistician Abraham Wald pointed out: They should armor where the survivors were NOT hit — planes hit there didn’t return.
Why It Matters
Business: We study successful companies, not failed ones. Survivors’ strategies may not be replicable. Self-help: “I woke at 4 AM and became CEO” — Ignores millions who woke at 4 AM and failed. Investing: Fund performance ads show winners, hide losers. Art/Music: We hear the hits, not the thousands of similar songs that flopped.
The Error
| We See | We Miss | Conclusion |
|---|---|---|
| Successful startups | Failed startups | ”Startups are a good bet” |
| Old books | Forgotten books | ”Books last forever” |
| Healthy 90-year-olds | Dead 90-year-olds | ”Smoking isn’t that bad” |
Fighting It
- Seek the graveyard — What happened to those who tried and failed?
- Ask about base rates — What % succeed vs fail?
- Consider luck — How much is skill vs chance?
- Look for counter-examples — Who did the same thing and failed?
Related Biases
- Availability Heuristic — Winners are available, losers aren’t
- [[Halo Effect** — Success makes everything seem right
- [[Narrative Fallacy** — We love success stories
Audio
Podcast episode: Survivorship Bias
Part of the Cognitive Bias Reference