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Biometrics

Title:		A semiparametric model for the analysis of recurrent-event panel data
Author(s):		Balshaw RF; Dean CB;
Address:		"Simon Fraser University, Burnaby, British Columbia, Canada. rbalshaw@stat.sfu.ca"
Journal Title:		Biometrics
Year:		2002
Volume:		58
Issue:		2
Page Number:		324 - 331
DOI:		10.1111/j.0006-341x.2002.00324.x
ISSN/ISBN:		0006-341X (Print) 0006-341X (Linking)
Abstract:		"In many longitudinal studies, interest focuses on the occurrence rate of some phenomenon for the subjects in the study. When the phenomenon is nonterminating and possibly recurring, the result is a recurrent-event data set. Examples include epileptic seizures and recurrent cancers. When the recurring event is detectable only by an expensive or invasive examination, only the number of events occurring between follow-up times may be available. This article presents a semiparametric model for such data, based on a multiplicative intensity model paired with a fully flexible nonparametric baseline intensity function. A random subject-specific effect is included in the intensity model to account for the overdispersion frequently displayed in count data. Estimators are determined from quasi-likelihood estimating functions. Because only first- and second-moment assumptions are required for quasi-likelihood, the method is more robust than those based on the specification of a full parametric likelihood. Consistency of the estimators depends only on the assumption of the proportional intensity model. The semiparametric estimators are shown to be highly efficient compared with the usual parametric estimators. As with semiparametric methods in survival analysis, the method provides useful diagnostics for specific parametric models, including a quasi-score statistic for testing specific baseline intensity functions. The techniques are used to analyze cancer recurrences and a pheromone-based mating disruption experiment in moths. A simulation study confirms that, for many practical situations, the estimators possess appropriate small-sample characteristics"
Keywords:		"Animals Biometry Data Interpretation, Statistical Female Humans Likelihood Functions Male Models, Biological *Models, Statistical Moths/drug effects/physiology Neoplasm Recurrence, Local/drug therapy Sex Attractants/pharmacology Urinary Bladder Neoplasms/;"
Notes:		"MedlineBalshaw, Robert F Dean, C B eng Research Support, Non-U.S. Gov't 2002/06/20 Biometrics. 2002 Jun; 58(2):324-31. doi: 10.1111/j.0006-341x.2002.00324.x"