注 :Ｔ :真的 ;Ｐ :阳性 ;Ｆ :假的 ;Ｎ :阴性 ;阳性预测值 :试验阳性者中真正有病者所占比例 ;阴性预测值 :试验阴性者中真正有病者所占比例 ;敏感性 :即真正有病者中试验阳性者所占比例 ;特异性 :即真正无病者中试验阴性者所占比例　　应用四格表时 ,必须保持敏感性及特异性 Note: T: true; P: positive; F: false; N: negative; positive predictive value: the proportion of patients with positive disease in the positive test; negative predictive value: Proportion: Sensitivity: the proportion of patients who are tested positive in the actual illness; Specificity: the proportion of patients who are tested negative in the real disease-free ratio The sensitivity and specificity