JSM 2012 Home

JSM 2012 Online Program

The views expressed here are those of the individual authors and not necessarily those of the JSM sponsors, their officers, or their staff.

Online Program Home

Abstract Details

Activity Number: 268
Type: Invited
Date/Time: Tuesday, July 31, 2012 : 8:30 AM to 10:20 AM
Sponsor: ENAR
Abstract - #303484
Title: A New U-Statistic with Superior Design Sensitivity in Matched Observational Studies
Author(s): Paul R Rosenbaum*+
Companies: University of Pennsylvania
Address: , , PA, ,
Keywords: Design sensitivity ; Observational study ; Randomization inference ; Sensitivity analysis ; U-statistic

In an observational study of treatment effects, a sensitivity analysis indicates the magnitude of bias from unmeasured covariates that would alter the conclusions. The power of a sensitivity analysis is the probability that it will reject a false hypothesis about treatment effects allowing for a departure from random assignment of a specified magnitude; in particular, if this specified magnitude is "no departure" then this is the power of a randomization test. A new family of u-statistics is proposed that includes Wilcoxon's signed rank statistic but also includes other statistics with substantially higher power when a sensitivity analysis is performed in an observational study. In one situation with 250 pair differences that are Normal with expectation 1/2 and variance 1, the power of a sensitivity analysis that uses Wilcoxon's statistic is 0.08 while the power of another u-statistics is 0.66. The topic is examined by performing a sensitivity analysis in three observational studies, using an asymptotic measure called the design sensitivity, and by simulating power in finite samples. The three examples are drawn from epidemiology, clinical medicine and genetic toxicology.

The address information is for the authors that have a + after their name.
Authors who are presenting talks have a * after their name.

Back to the full JSM 2012 program

2012 JSM Online Program Home

For information, contact jsm@amstat.org or phone (888) 231-3473.

If you have questions about the Continuing Education program, please contact the Education Department.