Noise: A Flaw in Human Judgment

Imagine that two doctors in the same city give different diagnoses to identical patients — or that two judges in the same court give different sentences to people who have committed the same crime. Suppose that different food inspectors give different ratings to indistinguishable restaurants — or that when a company is handling customer complaints, the resolution depends on who happens to be handling the particular complaint. Now imagine that the same doctor, the same judge, the same inspector, or the same company official make different decisions, depending on whether it is morning or afternoon, or Monday rather than Wednesday. These are examples of noise: variability in judgments that should be identical.

In Noise, Daniel Kahneman, Olivier Sibony, and Cass R. Sunstein show how noise helps produce errors in many fields, including medicine, law, public health, economic forecasting, food safety, forensic science, bail verdicts, child protection, strategy, performance reviews and personnel selection. And although noise can be found wherever people make judgments and decisions, individuals and organizations alike commonly ignore to its role in their judgments and in their actions. They show “noise neglect.” With a few simple remedies, people can reduce both noise and bias, and so make far better decisions.

Packed with new ideas, and drawing on the same kind of diligent, insightful research that made Thinking, Fast and Slow and Nudge groundbreaking New York Times and international bestsellers, Noise explains how and why humans are so susceptible to noise in judgment — and what we can do about it.