American Journal of Epidemiology Vol. 131, No. 1: 151-159
Copyright © 1990 by The Johns Hopkins University School of Hygiene and Public Health
research-article |
MATCHING AND EFFICIENCY IN COHORT STUDIES
Division of Epidemiology, UCLA School of Public Health Los Angeles, CA
Contrary to the impression given in some textbooks, matching can reduce the efficiency of a cohort study, even when it produces no sample-size reduction and even if the matching variable is a confounder. The authors illustrate this along with some additional points regarding cohort matching. First, the impact of matching on efficiency can be in opposite directions for different measures of effect; as a consequence, criteria for deciding whether to match must depend on whether one wishes to estimate relative or absolute effects. Second, the commonly drawn analogy between blocking in randomized trials and matching in cohort studies is misleading when one considers the impact of matching on covartate distributions. Third, the conditions for efficiency overmatching in a cohort study are different from the conditions in a case-control study. It appears that, under an additive model, matching will usually increase the efficiency of both risk-difference and risk-ratio estimation, and the power of the Mantel-Haenszel test. Under a multiplicative model, the impact of matching is not as consistently beneficial. The authors present some approximate criteria which allow one to use a priori information to predict whether cohort matching is likely to improve efficiency.
epidemiologic methods
CiteULike 
Connotea 
Del.icio.us What's this?
This article has been cited by other articles:
|
|
 |
|
  G. Y. Zou One relative risk versus two odds ratios: implications for meta-analyses involving paired and unpaired binary data Clinical Trials, February 1, 2007; 4(1): 25 - 31. [Abstract] [PDF]
|
|
|
|
 |
|
 S.-L. T Normand, K. Sykora, P. Li, M. Mamdani, P. A Rochon, and G. M Anderson Readers guide to critical appraisal of cohort studies: 3. Analytical strategies to reduce confounding BMJ, April 30, 2005; 330(7498): 1021 - 1023. [Full Text] [PDF]
|
|
|
|
 |
|
 A. Karpur, H. B. Clark, P. Caproni, and H. Sterner Transition to Adult Roles for Students With Emotional/Behavioral Disturbances: A Follow-Up Study of Student Exiters From Steps-to-Success Career Development for Exceptional Individuals, January 1, 2005; 28(1): 36 - 46. [Abstract] [PDF]
|
|
|
|
 |
|
 K. C. Chang, C. C. Leung, W. W. Yew, S. C. Ho, and C. M. Tam A Nested Case-Control Study on Treatment-related Risk Factors for Early Relapse of Tuberculosis Am. J. Respir. Crit. Care Med., November 15, 2004; 170(10): 1124 - 1130. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 P. Cummings, B. McKnight, and S. Greenland Matched Cohort Methods for Injury Research Epidemiol. Rev., August 1, 2003; 25(1): 43 - 50. [Full Text] [PDF]
|
|
|
|
 |
|
 H. M. Klaren, L. J. van't Veer, F. E. van Leeuwen, and M. A. Rookus Potential for Bias in Studies on Efficacy of Prophylactic Surgery for BRCA1 and BRCA2 Mutation J Natl Cancer Inst, July 2, 2003; 95(13): 941 - 947. [Full Text] [PDF]
|
|
|
|
|
|
M. Helms, P. Vastrup, P. Gerner-Smidt, K. Molbak, and S. Evans Short and long term mortality associated with foodborne bacterial gastrointestinal infections: registry based study * Commentary: matched cohorts can be useful BMJ, February 15, 2003; 326(7385): 357 - 357. [Abstract] [Full Text] [PDF]
|
|