ATS
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
QUICK SEARCH:   [advanced]


     

This Article
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Add to Personal Folders
Right arrow Download to citation manager
Right arrow Permission Requests
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Weinstein, G. S.
Right arrow Articles by Levin, B.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Weinstein, G. S.
Right arrow Articles by Levin, B.

The Annals of Thoracic Surgery, Vol 48, 490-495, Copyright © 1989 by The Society of Thoracic Surgeons

ARTICLES

Effect of crossover on the statistical power of randomized studies

GS Weinstein and B Levin
Division of Cardiothoracic Surgery, Long Island Jewish Medical Center, New Hyde Park, New York.

Randomized studies involving long-term follow-up are vulnerable to the effects of unplanned crossover. In surgical studies, such crossover usually occurs when control patients become more symptomatic and undergo operation. In several large studies of coronary bypass grafting, crossover ranged from 25% to 38%. The most common way of dealing with this problem is to apply the "intention-to-treat" principle, which analyzes such crossovers with their originally assigned groups. Besides the logical problem of counting a control patient who actually undergoes operation as "nonsurgical," a more subtle problem arises in terms of statistical power. When statistical power is low, a truly effective treatment may be mistakenly labeled as no better than control, causing a potentially valuable form of therapy to be ignored or discarded. This analysis demonstrates that crossover may have a profound effect on the statistical power of randomized studies and presents a method for predicting the effect of such crossover on statistical power.


This article has been cited by other articles:


Home page
 American Behavioral ScientistHome page
L. W. Sherman and H. Strang
Verdicts or Inventions?: Interpreting Results from Randomized Controlled Experiments in Criminology
American Behavioral Scientist, January 1, 2004; 47(5): 575 - 607.
[Abstract] [PDF]

Home page
 Med Decis MakingHome page
G. W. Torrance, M. F. Drummond, and V. Walker
Switching Therapy in Health Economics Trials: Confronting the Confusion
Med Decis Making, July 1, 2003; 23(4): 335 - 340.
[Abstract] [PDF]

Home page
 Journal of Research in Crime and DelinquencyHome page
P. R. GARTIN
Dealing with Design Failures in Randomized Field Experiments: Analytic Issues Regarding the Evaluation of Treatment Effects
Journal of Research in Crime and Delinquency, November 1, 1995; 32(4): 425 - 445.
[Abstract] [PDF]

Home page
 Journal of Research in Crime and DelinquencyHome page
L. W. SHERMAN
Defiance, Deterrence, and Irrelevance: A Theory of the Criminal Sanction
Journal of Research in Crime and Delinquency, November 1, 1993; 30(4): 445 - 473.
[Abstract] [PDF]

Home page
 ANN INTERN MEDHome page
O. N. Nwasokwa, J. H. Koss, G. H. Friedman, A. M. Grunwald, and M. M. Bodenheimer
Bypass Surgery for Chronic Stable Angina: Predictors of Survival Benefit and Strategy for Patient Selection
Ann Intern Med, June 1, 1991; 114(12): 1035 - 1049.
[Abstract] [PDF]


HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
ANN THORAC SURG ASIAN CARDIOVASC THORAC ANN EUR J CARDIOTHORAC SURG
J THORAC CARDIOVASC SURG ICVTS ALL CTSNet JOURNALS
Copyright © 1989 by The Society of Thoracic Surgeons.