Relationship Between Obuchowski-Rockette and Gallas U-Statistic Methods for Analyzing Multi-Reader Diagnostic Imaging Data

• Activity Number: 227 - Recent Advances in the Design and Analysis of Multi-Reader Imaging Studies
• Type: Topic Contributed
• Date/Time: Monday, July 29, 2019 : 2:00 PM to 3:50 PM
• Sponsor: Section on Medical Devices and Diagnostics
• Author(s): Stephen Hillis*
• Companies: University of Iowa
• Keywords: Obuchowski-Rockette; diagnostic radiology; AUC; U-statistic; Brandon Gallas; MRMC

Abstract

The Obuchowski-Rockette (OR) and Gallas U-statistic (U-stat) methods have been the two most frequently used methods for analyzing multireader multicase (MRMC) diagnostic imaging data that allow conclusions to generalize to both the reader and case populations. The OR method is the more general method because it can be used with any reader-performance measure, whereas the U-stat method is limited to a U-statistic outcome, such as the empirical (or trapezoidal) AUC statistic. On the other hand, advantages of the U-stat method are that it provides exact expressions for the outcome variance, provides unbiased variance estimates, and makes it easy to size future studies having a different abnormal-to-normal case ratio than was used in a pilot study. In this talk I discuss a particular version of the OR method that produces the same test statistic as the U-stat method. This new OR version uses a new way to estimate the error covariances which utilizes the U-stat approach. I show analytically that this version of the OR method produces the same test statistic as the U-stat method and discuss the useful implications of this result.