This article discusses extensions of generalized linear models for the analysis of longitudinal data. Two approaches are considered: subject-specific (SS) models in which heterogeneity in regression parameters is explicitly modelled; and population-averaged (PA) models in which the aggregate response for the population is the focus. We use a generalized estimating equation approach to fit both ...

Here is established the global existence of smooth solutions to a generalized nonlinear equation of Schrödinger type in the usual Sobolev spaces H and certain weighted Sobolev spaces by using Leray-Schauder fixed point theorem and delicate a priori estimates.

An algorithm is given for computing a weighted sum of a nondominant solution of a linear second-order inhomogeneous difference equation to a prescribed accuracy by estimating the truncation error. The present method is an extension of both the stable numerical method due to Olver and Sookne and a summation technique due to Deuflhard for computing minimal solutions of a homogeneous difference eq...

PLS Path Modeling and Generalized Structured Component Analysis are two component-based approaches to Structural Equation Models. Both methods aim at estimating the causal relationships linking two or more latent variables by means of a set of observed indicators. Moreover, both methods define the latent variable as a linear combination of its own observed variables, i.e. as a component. The ma...

BACKGROUND "Let Us Protect Our Future" is a sexual risk-reduction intervention for sixth-grade adolescents in South Africa. Tested in a cluster-randomized controlled trial, the intervention significantly reduced self-reported intercourse and unprotected intercourse during a 12-month follow-up period. PURPOSE The present analyses were conducted to identify moderators of the intervention's effi...

The purpose of this study was to determine the extent of leisure boredom, and investigate the relationship between leisure boredom, substance use and demographic variables among high school students in Cape Town, South Africa. 621 students from 39 high schools selected through a multistage cluster sampling procedure completed a questionnaire which measured substance use and demographic informat...

High-dimensional longitudinal data arise frequently in biomedical and genomic research. It is important to select relevant covariates when the dimension of the parameters diverges as the sample size increases. We consider the problem of variable selection in high-dimensional linear models with longitudinal data. A new variable selection procedure is proposed using the smooth-threshold generaliz...

We consider a class of doubly weighted rank-based estimating methods for the transformation (or accelerated failure time) model with missing data as arise, for example, in case-cohort studies. The weights considered may not be predictable as required in a martingale stochastic process formulation. We treat the general problem as a semiparametric estimating equation problem and provide proofs of...

In this paper, we demonstrate the importance of conducting well-thought-out sensitivity analyses for handling clustered data (data in which individuals are grouped into higher order units, such as students in schools) that arise from cluster randomized controlled trials (RCTs). This is particularly relevant given the rise in rigorous impact evaluations that use cluster randomized designs across...