A two-part mixed-effects pattern mixture model to handle zero-inflation and incompleteness in a longitudinal setting
Maruotti, Antonello (2011) A two-part mixed-effects pattern mixture model to handle zero-inflation and incompleteness in a longitudinal setting. Biometrical Journal, 53, (5), 716-734. (doi:10.1002/bimj.201000190). (PMID:21887792).
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Two-part regression models are frequently used to analyze longitudinal count data with excess zeros, where the same set of subjects is repeatedly observed over time. In this context, several sources of heterogeneity may arise at individual level that affect the observed process. Further, longitudinal studies often suffer from missing values: individuals dropout of the study before its completion, and thus present incomplete data records. In this paper, we propose a finite mixture of hurdle models to face the heterogeneity problem, which is handled by introducing random effects with a discrete distribution; a pattern-mixture approach is specified to deal with non-ignorable missing values. This approach helps us to consider overdispersed counts, while allowing for association between the two parts of the model, and for non-ignorable dropouts. The effectiveness of the proposal is tested through a simulation study. Finally, an application to real data on skin cancer is provided.
|Subjects:||H Social Sciences > HA Statistics|
|Divisions:||Faculty of Social and Human Sciences > Southampton Statistical Sciences Research Institute
Faculty of Social and Human Sciences > Mathematical Sciences > Statistics
|Date Deposited:||18 Jul 2012 14:21|
|Last Modified:||06 Dec 2012 15:41|
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