Where does representativeness collide?

In cognitive psychology, representativeness is a mental shortcut for judging how likely something is by how closely it resembles a typical case or stereotype, rather than by how common it actually is. Kahneman and Tversky's 1972 Subjective probability: A judgment of representativeness showed that people read probability off similarity, which leads them to ignore base rates, and Tversky and Kahneman's 1983 study of the conjunction fallacy showed the same shortcut can make a detailed, plausible story seem more likely than the broader category that fully contains it. Here the word names a flaw in reasoning, a resemblance judgment standing in for a probability, which is the opposite of the statistical virtue of a sample that faithfully mirrors a population, and different again from a body that speaks for its members.[1][2]

Unit

A single probability judgment made by resemblance to a type

Recovery means

Not applicable

Measured by

Elicited in experiments by comparing intuitive probability rankings against base rates and against correct set relations

In survey and sampling statistics, representativeness is a property of a sample: how far its make-up matches the population it was drawn from, so that estimates from the sample carry over to the whole. Kruskal and Mosteller's 1979 review Representative sampling catalogued the many ways the term is used across the literature and warned that it carries several distinct meanings, from mere absence of gross bias to a small-scale replica of the population. Here the word names a desirable feature of a well drawn sample, a faithful match between a part and the whole, not a mistake in reasoning as in psychology, and not a body of elected members as in political science.[3]

Unit

One sample, scored by how well its make-up matches the population

Recovery means

Not applicable

Measured by

Assessed by comparing sample margins against known population figures, or by the sampling design that fixes selection probabilities

In political science, representation is the relationship by which one person or body acts for a larger group, and representativeness asks how far the representatives resemble or answer to the represented. Pitkin's 1967 book The Concept of Representation drew the lasting distinction between descriptive representation, where a body mirrors the population in traits such as background, and substantive representation, where it acts in the interests of the represented whatever its make-up. Here the word names a feature of a governing or deliberative body, either mirroring a population or acting for it, which is neither a reasoning shortcut nor a statistical property of a random sample.[4]

Unit

A representative body, judged by how it mirrors or acts for a population

Recovery means

Not applicable

Measured by

Studied by comparing the make-up of a legislature to the electorate, and by whether its decisions track constituents' interests