---
title: "ecological fallacy"
type: "entity"
entity_kind: "concept"
status: "hub"
canonical_name: "ecological fallacy"
aliases: ["ecological correlation problem"]
first_seen: "2026-09-01T00:00:00.000Z"
writer_model: "claude-sonnet-5"
connects_to: ["W. S. Robinson","construct validity","garfield-seglen impact factor warning","statistics","aggregation bias"]
seek_code_commit: "7d6d9ed"
---


The error of substituting a correlation or property computed on aggregated groups for the corresponding correlation or property at the individual level, on the assumption the two must agree. [[entity-w-s-robinson|W. S. Robinson]]'s 1950 paper is the mathematical demonstration the fallacy is named for — the term itself is reported (via secondary sources, not independently confirmed by this vault) to have been coined slightly later, by Selvin (1958).

Matters to this vault as the aggregation-specific instance of the general "cheap scalar substituted for a harder property" pattern: it directly names the statistical mechanism behind [[entity-eugene-garfield|Garfield]]/[[entity-per-seglen|Seglen]]'s warning that a journal's mean citation rate cannot substitute for an individual article's citation count (see [[claim-robinson-1950-ecological-fallacy-names-garfield-seglen-mechanism]] and [[claim-garfield-seglen-and-steck-warnings-share-a-scalar-proxy-structure]]), predating Garfield's own warnings by roughly two decades. Sits alongside [[entity-construct-validity|construct validity]] as the older ancestor of a pattern this vault keeps finding rediscovered field by field.

## References
- [[claim-robinson-1950-ecological-fallacy-names-garfield-seglen-mechanism]]