ROC (receiver operating characteristic) curve is used to determine of cutpoints for screening or diagnostic tests. It have been widely used in Epidemiology area. Usually we use logistic regression to get this kind curve. If anyone knows how to get this curve and do statistic test for two curve, do please let me know too. Thanks in advance. Yiling Cheng -----Original Message----- From: baron at cattell.psych.upenn.edu [mailto:baron at cattell.psych.upenn.edu] Sent: Friday, February 01, 2002 11:17 AM To: jg_liao at yahoo.com; r-help at stat.math.ethz.ch Subject: Re: [R] ROC curves using R What is it that you want to compute? I have a set of scripts - written by my colleaged David Brainard in Matlab and translated to R by me - which we used to teach signal-detection theory in a grad "methods" course. But they are very straightforward and not worth putting into a package. (I'm sure there is something much more sophisticated one can do, but you don't say what.) Some useful R functions (illustrated, and probably self-explanatory): zHit <- qnorm(Ph) zFa <- qnorm(Pfa) dPrime <- zHit-zFa zCr <- qnorm(1-Pfa) Beta <- dnorm(zCr,dPrime,1)/dnorm(zCr,0,1) And here is the optimal "beta" (criterion): logBetaOpt <- log((pn/ps)*(Vcr + Vfa)/(Vh + Vm)) Jon Baron -.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-. -.- r-help mailing list -- Read http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html Send "info", "help", or "[un]subscribe" (in the "body", not the subject !) To: r-help-request at stat.math.ethz.ch _._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._. _._ -.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.- r-help mailing list -- Read http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html Send "info", "help", or "[un]subscribe" (in the "body", not the subject !) To: r-help-request at stat.math.ethz.ch _._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._
ROC curves using R
2 messages · Cheng, Yiling, Frank E Harrell Jr
For the purposes for which you mention, using ROC curves results in a number of serious problems. Full post-test probability models are generally recommended, without dichotomization of post-test probabilities until the point at which individual-patient utilities can be estimated. Frank Harrell On Fri, 1 Feb 2002 14:27:07 -0600
"Cheng, Yiling" <ycheng at cooperinst.org> wrote:
ROC (receiver operating characteristic) curve is used to determine of cutpoints for screening or diagnostic tests. It have been widely used in Epidemiology area. Usually we use logistic regression to get this kind curve. If anyone knows how to get this curve and do statistic test for two curve, do please let me know too. Thanks in advance. Yiling Cheng -----Original Message----- From: baron at cattell.psych.upenn.edu [mailto:baron at cattell.psych.upenn.edu] Sent: Friday, February 01, 2002 11:17 AM To: jg_liao at yahoo.com; r-help at stat.math.ethz.ch Subject: Re: [R] ROC curves using R What is it that you want to compute? I have a set of scripts - written by my colleaged David Brainard in Matlab and translated to R by me - which we used to teach signal-detection theory in a grad "methods" course. But they are very straightforward and not worth putting into a package. (I'm sure there is something much more sophisticated one can do, but you don't say what.) Some useful R functions (illustrated, and probably self-explanatory): zHit <- qnorm(Ph) zFa <- qnorm(Pfa) dPrime <- zHit-zFa zCr <- qnorm(1-Pfa) Beta <- dnorm(zCr,dPrime,1)/dnorm(zCr,0,1) And here is the optimal "beta" (criterion): logBetaOpt <- log((pn/ps)*(Vcr + Vfa)/(Vh + Vm)) Jon Baron -.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-. -.- r-help mailing list -- Read http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html Send "info", "help", or "[un]subscribe" (in the "body", not the subject !) To: r-help-request at stat.math.ethz.ch _._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._. _._ -.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.- r-help mailing list -- Read http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html Send "info", "help", or "[un]subscribe" (in the "body", not the subject !) To: r-help-request at stat.math.ethz.ch _._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._
Frank E Harrell Jr Prof. of Biostatistics & Statistics Div. of Biostatistics & Epidem. Dept. of Health Evaluation Sciences U. Virginia School of Medicine http://hesweb1.med.virginia.edu/biostat -.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.- r-help mailing list -- Read http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html Send "info", "help", or "[un]subscribe" (in the "body", not the subject !) To: r-help-request at stat.math.ethz.ch _._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._