目的建立一种基于灵敏度(SEN)和特异度(SPE)任意赋权的加权比数积统计方法。方法加权比数积(φw)的构造满足以下三个原则:灵敏度和特异度的权重(w)之和为1,0≤w≤1;满足特殊性:当灵敏度和特异度等权时,即w=0.5时,加权比数积φw等于比数积φ;加权比数积φw的取值范围与比数积φ的取值范围相同,为[0,+∞]。所构造的加权比数积为:φw=(SEN/(1-SEN))^2w·(SPE/(1-SPE))^2(1-w),(0≤w≤1)。根据中心极限定理,推导出lnφw的标准误和两个lnφw比较的Z统计推断方法,进一步推导出权重w的变化对检验统计量Z的影响。结果所构造的加权比数积满足上述构造三个原则。结论本研究所建立的加权比数积方法解决了应用中对灵敏度和特异度有不同赋权要求的问题,为诊断试验评价提供了新的工具。
Objective To develop a weighted odds product( φw) method for evaluating and comparing diagnostic tests based on weighted sensitivity and specificity. Methods Three principles of constructing weighted odds product φw are as follows:firstly,the sum of two weights which are attached to the sensitivity and specificity should equal to 1; secondly,φw equals to φ when the sensitivity and specificity have the same weights. finally the range of possible values of φw is within [0,+ ∞ ],which is the same as the odds product φ. Then,the φw is defined by φw =(SEN/(1- SEN)) ^2w ·( SPE/(1- SPE))^2( 1- w)( 0≤w≤1). According to the central- limit theorem,we obtain the standard error of lnφw and propose a statistical inference method to compare two weighted indexes. Furthermore,we also deduce the test statistics Z can be either a monotonously increasing /decreasing function or non- monotone function of the weight w under different conditions. Results The proposed φw satisfied the above-mentioned three principles. Conclusion For different weights attached to the sensitivity and specificity,φw can be used to deal with such kinds of problems as provide a new and practical tool to evaluate diagnostic tests.