The zero-inflated Poisson model and the decayed, missing and filled teeth index in dental epidemiology

被引:276
作者
Böhning, D
Dietz, E
Schlattmann, P
Mendonça, L
Kirchner, U
机构
[1] Free Univ Berlin, Inst Social Med, Dept Epidemiol, D-14195 Berlin, Germany
[2] Univ Fed Minas Gerais, Belo Horizonte, MG, Brazil
关键词
caries prevention study; decayed; missing and filled teeth index; mixture model; Poisson model with zero inflation; zero-inflated Poisson model graphics;
D O I
10.1111/1467-985X.00130
中图分类号
O1 [数学]; C [社会科学总论];
学科分类号
03 ; 0303 ; 0701 ; 070101 ;
摘要
For frequency counts, the situation of extra zeros often arises in biomedical applications. This is demonstrated with count data from a dental epidemiological study in Belo Horizonte (the Belo Horizonte caries prevention study) which evaluated various programmes for reducing caries. Extra zeros, however, violate the variance-mean relationship of the Poisson error structure. This extra-Poisson variation can easily be explained by a special mixture model, the zero-inflated Poisson (ZIP) model. On the basis of the ZIP model, a graphical device is presented which not only summarizes the mixing distribution but also provides visual information about the overall mean. This device can be exploited to evaluate and compare various groups. Ways are discussed to include covariates and to develop an extension of the conventional Poisson regression. Finally, a method to evaluate intervention effects on the basis of the ZIP regression model is described and applied to the data of the Belo Horizonte caries prevention study.
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页码:195 / 209
页数:15
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