Editors Reads Verdict
A necessary companion to Thinking, Fast and Slow — Kahneman and colleagues identify noise as an equally important but far less studied source of human judgment error, with profound practical implications.
What We Loved
- The bias/noise distinction is genuinely new conceptual work, not a repackaging of existing findings
- The practical implications — how to reduce noise in hiring, medicine, criminal sentencing — are spelled out with concrete detail
- The research on how noise operates in professional contexts (different doctors, different judges) is disturbing and important
Minor Drawbacks
- At 464 pages, it overstays its welcome — the core argument could be made in 200 pages without losing force
- Co-authored books sometimes lack the distinctive voice that made Kahneman's solo work so compelling
Key Takeaways
- → Bias (systematic error) and noise (random error) are independent problems — reducing one does not reduce the other
- → Noise in human judgment is vastly underestimated: two doctors seeing the same patient, two judges sentencing the same crime, will often reach very different conclusions
- → Decision hygiene — structured processes that reduce noise — is a more tractable problem than eliminating bias
| Author | Daniel Kahneman |
|---|---|
| Publisher | Little, Brown |
| Pages | 464 |
| Published | May 18, 2021 |
| Language | English |
| Genre | Non-Fiction, Psychology, Decision Making |
Noise Review
Noise is Daniel Kahneman’s return to the psychology of judgment, co-authored with Olivier Sibony and Cass Sunstein. Where Thinking, Fast and Slow focused on bias — the systematic, predictable ways that human cognition errs — Noise focuses on a different and less studied problem: random variability in human judgment that is neither systematic nor predictable.
The core distinction is this: a scale that consistently reads two kilograms too heavy is biased. A scale that gives a different reading every time is noisy. Human professional judgment, Kahneman and his co-authors argue, is both biased and noisy — and while bias has received enormous attention since Kahneman’s earlier work, noise is almost completely ignored, despite being equally costly.
The examples are striking. Studies of medical diagnosis find that two doctors examining the same imaging will often reach different conclusions. Studies of sentencing find that the same crime committed before the same judge will receive sentences that vary enormously based on factors that have nothing to do with the crime or the defendant — including, famously, whether the judge’s local sports team won or lost that morning. Insurance underwriters price the same risk differently depending on mood, time of day, and ambient temperature. All of this variability is costly and almost none of it is necessary.
The practical proposals — decision hygiene, structured assessments, statistical base rates — are the most prescriptive section of the book and the most useful for organizations seeking to improve their decision-making. Noise is drier than Thinking, Fast and Slow and less narratively unified, but it is doing genuinely new intellectual work and deserves to be read alongside its more celebrated predecessor.
Frequently Asked Questions
What is "Noise: A Flaw in Human Judgment" about?
Kahneman, Sibony, and Sunstein argue that human judgment suffers from two distinct problems: bias (consistent error) and noise (random variability). Noise is under-studied and under-corrected — and its costs in medicine, law, and business are enormous.
What are the key takeaways from "Noise: A Flaw in Human Judgment"?
Bias (systematic error) and noise (random error) are independent problems — reducing one does not reduce the other Noise in human judgment is vastly underestimated: two doctors seeing the same patient, two judges sentencing the same crime, will often reach very different conclusions Decision hygiene — structured processes that reduce noise — is a more tractable problem than eliminating bias
Is "Noise: A Flaw in Human Judgment" worth reading?
A necessary companion to Thinking, Fast and Slow — Kahneman and colleagues identify noise as an equally important but far less studied source of human judgment error, with profound practical implications.
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