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Activity Number:
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440
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Type:
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Contributed
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Date/Time:
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Wednesday, August 5, 2009 : 8:30 AM to 10:20 AM
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Sponsor:
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Section on Statistics in Epidemiology
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| Abstract - #305197 |
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Title:
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Penalized Splines in the Time-Varying Coefficient Rates Model
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Author(s):
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Leila D. Amorim*+ and Jianwen Cai and Donglin Zeng and Mauricio L. Barreto
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Companies:
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Universidade Federal da Bahia and The University of North Carolina at Chapel Hill and The University of North Carolina at Chapel Hill and Universidade Federal da Bahia
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Address:
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Rua Joaquim Ferraro do Nascimento, 102, apt.1003, Salvador-Bahia, International, 41927-440, Brazil
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Keywords:
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penalized splines ; marginal rates models ; recurrent events ; time-varying effects ; survival models
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Abstract:
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Methods have been proposed to explore the functional form of effects using splines with moderate number of knots, with parameters being estimated using penalized partial likelihoods in survival models. Research has also been conducted for development of estimation methods of means/rates of recurrent events. We propose a method that uses B-splines with small to moderate number of knots to estimate time-varying effects in the marginal rates model with estimation based on penalized partial likelihood. The proposed method is used to describe the functional form of the effect of vitamin A supplementation on the rate of recurrent diarrheal episodes in small children from Brazil. Simulation studies examined the finite-sample properties of the proposed parameter estimators. Overall, empirical sizes were closer to nominal level when considering small number of knots and large sample sizes.
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