title: Marginal Analysis of Longitudinal Count Data in Long Sequences: Methods and Applications to A Driving Study.
abstract: Most of the available methods for longitudinal data analysis are designed and validated for the situation where the number of subjects is large and the number of observations per subject is relatively small. Motivated by the Naturalistic Teenage Driving Study (NTDS), which represents the exact opposite situation, we examine standard and propose new methodology for marginal analysis of longitudinal count data in a small number of very long sequences. We consider standard methods based on generalized estimating equations, under working independence or an appropriate correlation structure, and find them unsatisfactory for dealing with time-dependent covariates when the counts are low. For this situation, we explore a within-cluster resampling (WCR) approach that involves repeated analyses of random subsamples with a final analysis that synthesizes results across subsamples. This leads to a novel WCR method which operates on separated blocks within subjects and which performs better than all of the previously considered methods. The methods are applied to the NTDS data and evaluated in simulation experiments mimicking the NTDS.
authors.affiliation: Division of Biostatistics, Center for Devices and Radiological Health, Food and Drug Administration, 10903 New Hampshire Ave. Silver Spring, Maryland 20993, USA.
authors.forename: Zhiwei
authors.initials: Z
authors.lastname: Zhang
authors.affiliation: Biostatistics and Bioinformatics Branch, Division of Epidemiology, Statistics and Prevention Research, Eunice Kennedy Shriver National Institute of Child Health and Human Development, 6100 Executive Blvd. Bethesda, Maryland 20892, USA.
authors.forename: Paul S
authors.initials: PS
authors.lastname: Albert
authors.affiliation: Prevention Research Branch, Division of Epidemiology, Statistics and Prevention Research, Eunice Kennedy Shriver National Institute of Child Health and Human Development, 6100 Executive Blvd. Bethesda, Maryland 20892, USA.
authors.forename: Bruce
authors.initials: B
authors.lastname: Simons-Morton
keywords: Correlation; generalized estimating equation; multiple outputation; overdispersion; random effect; separated blocks; within-cluster resampling