Noise: A Flaw in Human Judgment

by Daniel Kahneman

Like predictive judgments, evaluative judgments entail an expectation of bounded disagreement. No self-respecting federal judge is likely to say, “This is the punishment I like best, and I don’t care a bit if my colleagues think otherwise.” And decision makers who choose from several strategic options expect colleagues and observers who have the same information and share the same goals to agree with them, or at least not to disagree too much. Evaluative judgments partly depend on the values and preferences of those making them, but they are not mere matters of taste or opinion. For that reason, the boundary between predictive and evaluative judgments is fuzzy and people who make judgments are often unaware of it. Judges who set sentences or professors who grade essays think hard about their task and strive to find the “right” answer. They develop confidence in their judgments and in the justifications they have for them. Professionals feel much the same, act much the same, and speak much the same to justify themselves when their judgments are predictive (“How well will this new product sell?”) and when they are evaluative (“How well did my assistant perform this year?”).