摘要：The accuracy of a binary diagnostic test can easily be assessed by comparing the
sensitivity and specificity with the status of respondents. When the result of a diagnostic
test is continuous, the assessment of accuracy depends on a specified threshold.
The receiver operating characteristic (ROC) curve, which includes all possible combinations
of sensitivity and specificity, provides an appropriate measure for evaluating
the overall accuracy of the diagnostic test. Nevertheless, in practice, a cutoff value is
still required to make easier its clinical usage easier. The determination of a proper
cutoff value depends on how important the practitioner views the specificity and sensitivity.
Given particular values of specificity and sensitivity, this paper derives the
optimal cutoff value under two parametric assumptions on the outcomes of the diagnostic
test. Because the optimal cutoff value does not have a closed form, the
numerical results are tabulated for some parameter settings to find the optimal cutoff
value. Finally, real data are employed to illustrate the use of the proposed method.
