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A comparison of denominator degrees of freedom methods for multiple observer ROC analysis
Author(s) -
Hillis Stephen L.
Publication year - 2006
Publication title -
statistics in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.996
H-Index - 183
eISSN - 1097-0258
pISSN - 0277-6715
DOI - 10.1002/sim.2532
Subject(s) - dbm , computer science , degrees of freedom (physics and chemistry) , measure (data warehouse) , covariance , statistics , statistic , nominal level , confidence interval , test statistic , algorithm , mathematics , statistical hypothesis testing , data mining , bandwidth (computing) , amplifier , physics , quantum mechanics , computer network
There are several methods available for analysing multireader ROC studies that generalize results to both the reader and case populations. Two of these methods—the Dorfman–Berbaum–Metz (DBM) method and the Obuchowki–Rockette (OR) method—appear to be quite different in their original formulations. However, recently it has been shown that the DBM and OR procedures yield the same test statistic when based on the same accuracy measure and covariance estimation method, but inferences can vary depending on which denominator degrees of freedom (ddf) method, DBM or OR, is used. I show in simulations that there are problems with both ddf methods: OR is ultraconservative with significance levels considerably below the nominal level, and DBM can result in extremely wide confidence intervals because the ddf can be close to zero. I propose a new ddf method that overcomes both of these problems and can be used with either the OR or DBM procedure. Copyright © 2006 John Wiley & Sons, Ltd.