Rational brain · Judgment & Decision Science

Bayesian Updating

Start from a base rate, update incrementally on evidence in proportion to how diagnostic it is; the best forecasters do this and most people either ignore the prior or over-react to the latest data point.

An everyday example

A single glowing reference moving a hiring decision from 30% to 90%.

What it can cost you

Over-updating on vivid evidence, under-updating on dull evidence, and being fed evidence designed to move you.

Warning signs

  • One fact flipped my view.
  • I had no starting estimate.

One thing to do

For any new fact ask two questions: how likely is this if I am right, and how likely if I am wrong? Move only by the ratio.

Is this happening to you right now?

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Not medical, legal or financial advice. How Decision IQ works

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