No. 270 · Evidence · Heuristics and Bias
Survivorship Bias
When failures vanish from view, the survivors look like the whole story.
In the Almanac
“Wald’s missing bullet holes”, 1943 · “SPIVA scorecards”, 2002
Both stories in full, three ways to use it and where it misleads.
Get the AlmanacQuestions
What is Survivorship Bias?
Survivorship Bias is the error of studying only the survivors of a process. Because failures disappear from view, success looks easier and more predictable than it really is, and we copy habits that may have been pure luck.
How do you avoid Survivorship Bias?
To counter it, always ask where the missing cases are. Look for data that includes the failures, question success stories, and compare winners with losers before drawing any lesson.
When does Survivorship Bias matter?
Survivorship Bias is one of the 68 mental models for evidence, the situations where you ask: Is this really true? Within that, it belongs to “When research goes wrong”, alongside Anecdotal Evidence, Data Dredging and Hasty Generalisation.
What is an example of Survivorship Bias?
Two stories show it at work: Wald’s missing bullet holes (1943) and SPIVA scorecards (2002). Both are told in full in The Mental Models Daily Almanac, which has two stories for each of its 365 models.
Which mental models are related to Survivorship Bias?
Selection Bias, Cargo Cult and Hindsight Bias. Survivorship Bias itself comes from heuristics and bias.