Title
Modeling heterogeneity for count data : a study of maternal mortality in health facilities in Mozambique Modeling heterogeneity for count data : a study of maternal mortality in health facilities in Mozambique
Author
Faculty/Department
Faculty of Medicine and Health Sciences
Publication type
article
Publication
Subject
Mathematics
Biology
Computer. Automation
Source (journal)
Biometrical journal
Volume/pages
55(2013) :5 , p. 647-660
ISSN
0323-3847
ISI
000327816900001
Carrier
E
Target language
English (eng)
Full text (Publishers DOI)
Affiliation
University of Antwerp
Abstract
Count data are very common in health services research, and very commonly the basic Poisson regression model has to be extended in several ways to accommodate several sources of heterogeneity: (i) an excess number of zeros relative to a Poisson distribution, (ii) hierarchical structures, and correlated data, (iii) remaining unexplained sources of overdispersion. In this paper, we propose hierarchical zero-inflated and overdispersed models with independent, correlated, and shared random effects for both components of the mixture model. We show that all different extensions of the Poisson model can be based on the concept of mixture models, and that they can be combined to account for all different sources of heterogeneity. Expressions for the first two moments are derived and discussed. The models are applied to data on maternal deaths and related risk factors within health facilities in Mozambique. The final model shows that the maternal mortality rate mainly depends on the geographical location of the health facility, the percentage of women admitted with HIV and the percentage of referrals from the health facility.
E-info
https://repository.uantwerpen.be/docman/iruaauth/eb62ac/d086515.pdf
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