Dependence of weighted kappa coefficients on the number of categories
Dependence of weighted kappa coefficients on the number of categories
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DOI：
10.1097/00001648-199603000-00016
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发表时间：
1996-03-01
期刊：
影响因子：
5.4
通讯作者：
Kliebsch, U
中科院分区：
文献类型：
--
作者：
Brenner, H;Kliebsch, U
加权卡帕系数通常用于量化临床和流行病学应用中顺序评级的内部或内部可靠性或重测可靠性。在本文中，我们评估了加权 kappa 系数对类别数量和加权方案类型的依赖性，这些依赖性因应用程序而异。最常用的权重是与单个评级的偏差（“线性权重”）或与单个评级的偏差的平方（“二次权重”）成比例的权重。在某些条件下，二次加权 kappa 系数相当于类内相关系数和乘积矩相关系数。我们说明，在各种条件下，二次加权 kappa 系数预计会随着类别数量的增加而增加，而线性加权 kappa 系数似乎对类别数量不太敏感。因此，在解释加权 kappa 系数时需要仔细考虑类别数量和加权方案类型。
Weighted kappa coefficients are commonly used to quantify inter- or intra-rater reliability or test-retest reliability of ordinal ratings in clinical and epidemiologic applications. In this paper, we assess the dependence of weighted kappa coefficients on the number of categories and the type of weighting scheme, which vary between applications. The most commonly used weights are weights that are proportional to the deviation of individual ratings (''linear weights'') or to the square of the deviation of individual ratings (''quadratic weights''). Quadratically weighted kappa coefficients are equivalent to the intraclass correlation coefficient and to the product-moment correlation coefficient under certain conditions. We illustrate that an increase of quadratically weighted kappa coefficients with the number of categories is expected under a broad variety of conditions, whereas linearly weighted kappa coefficients appear to be less sensitive to the number of categories. Number of categories and type of weighting scheme therefore require careful consideration in the interpretation of weighted kappa coefficients.