Article citationsMore>>

Masaryk, A.M., Ross, J.S., DiCello, M.C., Modic, M.T., Paranandi, L. and Masaryk, T.J. (1991) 3DFT MR Angiography of the Carotid Bifurcation: Potential and Limitations as a Screening Examination. Radiology, 179, 797-804. http://dx.doi.org/10.1148/radiology.179.3.2027995

has been cited by the following article:

• TITLE: Optimal Weights in Nonparametric Analysis of Clustered ROC Curve Data

  AUTHORS: Yougui Wu

  KEYWORDS: Diagnostic Test, Optimal Weight, Asymptotic Relative Efficiency, Receiver Operating Characteristic Curve, Area under a ROC Curve

  JOURNAL NAME: Journal of Applied Mathematics and Physics, Vol.3 No.7, June 30, 2015

  ABSTRACT: In diagnostic trials, clustered data are obtained when several subunits of the same patient are observed. Within-cluster correlations need to be taken into account when analyzing such clustered data. A nonparametric method has been proposed by Obuchowski (1997) to estimate the Receiver Operating Characteristic curve area (AUC) for such clustered data. However, Obuchowski’s estimator gives equal weight to all pairwise rankings within and between cluster. In this paper, we modify Obuchowski’s estimate by allowing weights for the pairwise rankings vary across clusters. We consider the optimal weights for estimating one AUC as well as two AUCs’ difference. Our results in this paper show that the optimal weights depends on not only the within-patient correlation but also the proportion of patients that have both unaffected and affected units. More importantly, we show that the loss of efficiency using equal weight instead of our optimal weights can be severe when there is a large within-cluster correlation and the proportion of patients that have both unaffected and affected units is small.