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Estimating Risk Difference in Multicenter Studies Under Baseline‐Risk Heterogeneity
Author(s) -
Böhning Dankmar,
Sarol Jesus
Publication year - 2000
Publication title -
biometrics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.298
H-Index - 130
eISSN - 1541-0420
pISSN - 0006-341X
DOI - 10.1111/j.0006-341x.2000.00304.x
Subject(s) - estimator , statistics , mathematics , absolute risk reduction , difference in differences , baseline (sea) , variance (accounting) , econometrics , sample size determination , bias of an estimator , mean difference , medicine , minimum variance unbiased estimator , confidence interval , economics , biology , accounting , fishery
Summary. In this paper, we consider the case of efficient estimation of the risk difference in a multicenter study allowing for baseline heterogeneity. We consider the optimally weighted estimator for the common risk difference and show that this estimator has considerable bias when the true weights (which are inversely proportional to the variances of the center‐specific risk difference estimates) are replaced by their sample estimates. In addition, we propose a new estimator for this situation of the Mantel‐Haeiiszel type that is unbiased and, in addition, has a smaller variance for small sample sizes within the study centers. Simulations illustrate these findings.