Cohen's kappa

Linguistics

Philosophy

Kappa

Statistics

Interpretation (philosophy)

Agreement

Data mining

Computer science

Statistic

Mathematics

Geometry

Measure (data warehouse)

Programming language

PubMed

Items such as physical exam findings, radiographic interpretations, or other diagnostic tests often rely on some degree of subjective interpretation by observers. Studies that measure the agreement between two or more observers should include a statistic that takes into account the fact that observers will sometimes agree or disagree simply by chance. The kappa statistic (or kappa coefficient) is the most commonly used statistic for this purpose. A kappa of 1 indicates perfect agreement, whereas a kappa of 0 indicates agreement equivalent to chance. A limitation of kappa is that it is affected by the prevalence of the finding under observation. Methods to overcome this limitation have been described.

Understanding interobserver agreement: the kappa statistic.