1. Analysing repeated measurements with possibly missing observations by modelling marginal distributions.
- Author
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Wei LJ and Stram DO
- Subjects
- Child, Humans, Longitudinal Studies, Models, Biological, Regression Analysis, Tennessee, Tobacco Smoke Pollution, Wisconsin, Air Pollution, Chenodeoxycholic Acid pharmacology, Cholesterol blood, Lung Diseases epidemiology, Statistics as Topic
- Abstract
Suppose that subjects are observed repeatedly over a common set of time points with possibly time-dependent covariates and possibly missing observations. At each time point we model the marginal distribution of the response variable and the effect of the covariates on that distribution using a class of quasi-likelihood models studied in McCullagh and Nelder. No parametric model of dependence of the repeated observations of the subject is assumed. For large samples, the quasi-likelihood estimates of the time-specific regression coefficients over the set of predetermined time points are shown to be approximately jointly normal. This, coupled with various inference procedures, provides a global picture about the effects of the covariates on the response variable over the entire study period. A lack-of-fit test for testing the adequacy of the assumed quasi-likelihood model is also provided. All the methods considered here are illustrated with real-life examples.
- Published
- 1988
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