Noise

Two doctors in the same city examine identical patients and reach different diagnoses. Two judges in the same courthouse hand down different sentences for the same crime. Stranger still, a single doctor or judge may decide differently depending on the day of the week, the time of day, or whether lunch has happened yet. Daniel Kahneman, Olivier Sibony and Cass R. Sunstein call this unwanted variability in judgements that ought to match "noise".

The authors argue that noise is a hidden and costly source of error wherever people make decisions. They trace its effects through medicine, law, public health, economic forecasting, forensic science, child protection, creative strategy, performance reviews and hiring. Most people and organizations barely notice it, even though it quietly distorts outcomes that matter. Bias gets most of the attention in discussions of bad judgement, and this book makes the case that noise deserves equal scrutiny.

Building on the kind of analysis and varied case studies familiar from Kahneman's Thinking, Fast and Slow and Sunstein's Nudge, the book explains why humans are so prone to both noise and bias when they decide things. Its central point is uncomfortable: we make bad judgements far more often than we think.

The book does not stop at diagnosis. It also sets out a few simple remedies that individuals and organizations can use to make better, more consistent decisions.