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Activity Number:
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519
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Type:
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Invited
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Date/Time:
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Thursday, August 2, 2007 : 10:30 AM to 12:20 PM
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Sponsor:
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WNAR
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| Abstract - #307874 |
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Title:
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Modeling Heterogeneity in Intraclass Correlation
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Author(s):
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Catherine M. Crespi*+ and Weng-Kee Wong
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Companies:
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University of California, Los Angeles and University of California, Los Angeles
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Address:
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Department of Biostatistics, Los Angeles, CA, 90095-1772,
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Keywords:
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Generalized estimating equations ; Correlated data ; Group randomized trials ; Intraclass correlation
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Abstract:
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In cluster-randomized trials, it is commonly assumed that the magnitude of the correlation among subjects is invariant across clusters. However, the correlation may in fact vary among clusters due to the delivery of the intervention or cluster-level covariates. Failure to adequately model heterogeneity of the correlation may result in loss of efficiency. We present a method for modeling heterogeneous correlation structure using generalized estimating equations and demonstrate the use of goodness of fit criteria for choosing the best correlation structure. Application to a cluster-randomized trial of an educational intervention to promote cancer screening illustrates the methods.
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