Finding the Optimal Threshold of the Parametric ROC Curve under Continuous Diagnostic Measurement

• Main Authors: Hung, Yuhan, 洪郁涵
• Other Authors: Hwang, YiTing
• Format: Others
• Language: zh-TW
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/93101676073440303801

碩士 === 國立臺北大學 === 統計學系 === 100 === The accuracy of a binary diagnostic test can be assessed easily through comparing the results with the status of respondents. That is, the sensitivity and specificity are evaluated. However, when the diagnostic test is resulted in a continuous version, the accuracy depends upon the specified threshold. The ROC curve (receiver operating characteristic curve) that includes all possible combinations of sensitivity and specificity, provides a way to evaluate an overall evaluation of the diagnostic test. Nevertheless, in practice, a threshold is still needed to have an easier clinical representation. The determination of a proper threshold depends upon the definition of accuracy. The determination of the accuracy depends on how important the prac- titioner views the specificity and sensitivity. Given a particular concern of specificity and sensitivity, this thesis derives the optimal threshold under two commonly used parametric assumptions on the diagnostic test (Binor- mal model and Bilogistic model). Since the optimal threshold does not have a closed form, the numerical results are given in tables for many parameter settings, so the practitioner can easily find the optimal threshold for their studies.