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Decision-Making Under Uncertainty

Probabilistic Thinking & Base Rate Neglect

Level: advancedModel #26
thinking
Description

Most decisions require thinking in probabilities rather than certainties. Base rates—statistical information about how things generally work—provide crucial context, yet we systematically ignore them in favor of vivid stories or intuitions about our specific situation. This creates predictable errors in judgment that compound over time.

Applications
Start with base rates from a good reference class, then adjust based on specific evidence. A shy person is more likely to be a social scientist than a computer scientist when social scientists outnumber computer scientists ten to one, even though shyness feels more representative of programmers.
Separate decision quality from outcomes. Judge decisions by process, not results, and mind the sample size when learning from experience. In a bull market, everyone looks like a genius.
Practice probabilistic calibration by assigning percentages to beliefs and asking "what would make me say I'm wrong?" Getting comfortable with uncertainty—"I'm 70% confident"—improves judgment more than false precision.
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