No. 4 · Decisions · Systems
Decision Tree
Draw your choices as branches, and the questions that really matter come into view.
In the Almanac
“Chest pain in Chicago”, 1990s · “Chevron”, 1990s–2010s
Both stories in full, three ways to use it and where it misleads.
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Questions
What is Decision Tree?
A Decision Tree lays out each choice, what might happen next and the likely payoff as branches. At Chicago's Cook County Hospital, Lee Goldman's tree safely kept more low-risk patients out of cardiac beds, and Chevron uses decision trees for multibillion-dollar investments.
How do you use Decision Tree?
Sketch a quick tree for job offers or warranties, add rough probabilities, and look for the uncertainty that matters most. Or create simple if-then rules for health. Keep trees simple, because they're only as good as their inputs.
When does Decision Tree matter?
Decision Tree is one of the 35 mental models for decisions, the situations where you ask: Which way should I go? Within that, it belongs to “Weighing the options”, alongside A/B Testing, Back-of-the-Envelope Calculation and Cost-Benefit Analysis.
What is an example of Decision Tree?
Two stories show it at work: Chest pain in Chicago (1990s) and Chevron (1990s–2010s). 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 Decision Tree?
Expected Value, Scenario Analysis and Monte Carlo Simulation. Decision Tree itself comes from systems.