The noise this book investigates is the randomness inherent in every system. Daniel Kahneman along with authors Olivier Sibony and Cass R. Sunstein introduced this book with the perfect illustration. Imagine a target with a cluster of bullet holes around the target. The deviation from the centre is noise. If, however, the cluster is consistently off target, you’re dealing with bias.

Much has been written about bias, but less about noise. People don’t want to admit that noise exists, at least to the extent that it does. Take the following examples:

• Medical doctors diagnose the same patients differently
• Child custody decisions depend on the noisy discretion of case managers
• Forecasts of any sort (financial, weather, etc.) vary dramatically
• Forensic science such as fingerprint technology lead to inconsistent decisions
• Judicial sentencing varies dramatically depending on the judge

Kahneman, Sibony, and Sunstein bring all aspects of noise to light, illustrated by current research on the topic. In the end, the authors recommend decision hygiene—a process that takes noise into account and seeks to mitigate it. The appendix even includes instructions on how to conduct a “noise audit” (379–85).

The target audience for this book are decision-making professionals. It’s an urgent plea to account for randomness of decision-making, especially in situations where people’s lives depend upon it.

Kahneman, Daniel, et al., eds. Noise: A Flaw in Human Judgment. Little, Brown Spark, 2021.