Cicchetti D V, Feinstein A R
Yale University School of Medicine, New Haven, CT 06510.
J Clin Epidemiol. 1990;43(6):551-8. doi: 10.1016/0895-4356(90)90159-m.
An omnibus index offers a single summary expression for a fourfold table of binary concordance among two observers. Among the available other omnibus indexes, none offers a satisfactory solution for the paradoxes that occur with p0 and kappa. The problem can be avoided only by using ppos and pneg as two separate indexes of proportionate agreement in the observers' positive and negative decisions. These two indexes, which are analogous to sensitivity and specificity for concordance in a diagnostic marker test, create the paradoxes formed when the chance correction in kappa is calculated as a product of the increment in the two indexes and the increment in marginal totals. If only a single omnibus index is used to compared different performances in observer variability, the paradoxes of kappa are desirable since they appropriately "penalize" inequalities in ppos and pneg. For better understanding of results and for planning improvements in the observers' performance, however, the omnibus value of kappa should always be accompanied by separate individual values of ppos and pneg.
综合指数为两位观察者之间二元一致性的四格表提供了一个单一的汇总表达式。在现有的其他综合指数中，没有一个能为p0和kappa出现的悖论提供令人满意的解决方案。只有通过使用ppos和pneg作为观察者阳性和阴性决策中比例一致性的两个单独指标，才能避免这个问题。这两个指标类似于诊断标志物测试中一致性的敏感性和特异性，当kappa中的机会校正计算为两个指标的增量与边际总数增量的乘积时，就会产生悖论。如果仅使用一个综合指数来比较观察者变异性中的不同表现，kappa的悖论是可取的，因为它们适当地“惩罚”了ppos和pneg中的不平等。然而，为了更好地理解结果并规划观察者表现的改进，kappa的综合值应始终伴随着ppos和pneg的单独个体值。
