No. 237 · Evidence · Statistics and Probability
Probability Distribution
Good decisions weigh everything that could happen, not just the single most likely outcome.
In the Almanac
“Kicked by a horse”, 1898 · “Polymarket”, 2024
Both stories in full, three ways to use it and where it misleads.
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Questions
What is Probability Distribution?
A Probability Distribution maps the full range of outcomes, not just the most likely one. Ladislaus Bortkiewicz showed that deaths from horse kicks in the Prussian cavalry followed a steady, predictable pattern, and prediction markets like Polymarket turn prices into live probabilities.
How do you use Probability Distribution?
Use it by estimating ranges instead of single numbers, planning budgets for rough months rather than average ones, and checking real base rates before reacting to vivid stories. Redraw your picture whenever new evidence arrives.
When does Probability Distribution matter?
Probability Distribution is one of the 68 mental models for evidence, the situations where you ask: Is this really true? Within that, it belongs to “Reading the numbers”, alongside Base Rate Fallacy, Bayes’ Theorem and Central Limit Theorem.
What is an example of Probability Distribution?
Two stories show it at work: Kicked by a horse (1898) and Polymarket (2024). 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 Probability Distribution?
Expected Value, Prediction Market and Scenario Analysis. Probability Distribution itself comes from statistics and probability.