In other words, lies above the common covariate-specific ROC curve because the center with the most cases also tends to have higher marker levels.Failing to adjust for the covariate (center) leads to an overoptimistic measure of marker performance.However, it has received little attention in the growing area of medical research devoted to the development of markers for disease diagnosis, screening, or prognosis, where classification accuracy, rather than association, is of primary interest.In this paper, the authors demonstrate the need for covariate adjustment in studies of classification accuracy, discuss methods for adjusting for covariates, and distinguish covariate adjustment from several other related, but fundamentally different, uses for covariates.= 1, in the pooled data under scenario 1, and in the pooled data under scenario 2. B) The common covariate-specific receiver operating characteristic (ROC) curve, the pooled ROC curve under scenario 1, and the pooled ROC curve under scenario 2.The performances of the 2.5 thresholding rule are indicated.
A popular topic in medical research today is the development of markers to classify subjects as diseased or disease free, as high or low risk, or in terms of treatment response or another future event.
Although adjustment for covariates is commonplace in therapeutic and etiologic studies, the issue of covariate effects is not well appreciated in the classification setting.
In this paper, we demonstrate the need for covariate adjustment and describe statistical methods that can be used to accomplish it.
tutorial on SAS macro that is able to compute p-value for difference between two AUC ROC, explaining different statistical approachesmore technical: SAS help on nonparametric comparison of two ROC journal article reference and Rcode for three different methods of calculation of SE of AUC ROC. (Stephan Clin Chem 2003medcalc by SCHOONJANS - commercial sw for cox hazard, ROCJane, Longton, Pepe 2009: Accommodating Covariates in ROC Analysis ROC EXPLANATION(Fig. The practical lowerlimit for the AUC of a diagnostic test is 0.5.
(continuous, ordinal, skewed, sparse categories etc).*xxx* more technical-but - SUGI .... Rcode for the De Long method of AUC ROC SE estimation - nonparametric ROCKIT by prof Metz from CHICAGO, free, downloaded, but IMHO will t ake some time to get around, to prepare input file, things with bootstraping, jacknifing etc, nonparametric tests.- cf childhood predictors of young onset T2DM ... DIABETES 2007 = methods CF comparison of 8 software packages for performing ROC analysis.
The covariate-specific ROC curve calibrates the marker with respect to , as we will describe.