title: Kappa coefficient: a popular measure of rater agreement.
abstract: In mental health and psychosocial studies it is often necessary to report on the between-rater agreement of measures used in the study. This paper discusses the concept of agreement, highlighting its fundamental difference from correlation. Several examples demonstrate how to compute the kappa coefficient - a popular statistic for measuring agreement - both by hand and by using statistical software packages such as SAS and SPSS. Real study data are used to illustrate how to use and interpret this coefficient in clinical research and practice. The article concludes with a discussion of the limitations of the coefficient.
authors: Department of Biostatistics and Computational Biology, University of Rochester, Rochester, NY, United States.
authors: Wan
authors: W
authors: Tang
authors: College of Basic Science and Information Engineering, Yunnan Agricultural University, Kunming, Yunnan Province, China.
authors: Jun
authors: J
authors: Hu
authors: Department of Biostatistics, St. Jude Children's Research Hospital, Memphis, TN, United States.
authors: Hui
authors: H
authors: Zhang
authors: Value Institute, Christiana Care Health System, Newark, DE, United States.
authors: Pan
authors: P
authors: Wu
authors: Department of Biostatistics and Computational Biology, University of Rochester, Rochester, NY, United States ; Center of Excellence for Suicide Prevention, Canandaigua VA Medical Center Canandaigua, NY, United States.
authors: Hua
authors: H
authors: He
keywords: correlation; interrater agreement; weighted kappa