Analysis of longitudinal binary data from multiphase sampling

The efficient use of surrogate or auxiliary information has been investigated within both model-based and design-based approaches to data analysis, particularly in the context of missing data. Here we consider the use of such data in epidemiological studies of disease incidence in which surrogate measures of disease status are available for all subjects at two time points, but definitive diagnoses are available only in stratified subsamples. We briefly review methods for the analysis of two-phase studies of disease prevalence at a single time point, and we discuss the extension of four of these methods to the analysis of incidence studies. Their performance is compared with special reference to a study of the incidence of senile dementia.     

Evaluation of Tweedie exponential dispersion model densities by Fourier inversion

The Tweedie family of distributions is a family of exponential dispersion models with power variance functions V(μ)=μ ^p for . These distributions do not generally have density functions that can be written in closed form. However, they have simple moment generating functions, so the densities can be evaluated numerically by Fourier inversion of the characteristic functions. This paper develops numerical methods to make this inversion fast and accurate. Acceleration techniques are used to handle oscillating integrands. A range of analytic results are used to ensure convergent computations and to reduce the complexity of the parameter space. The Fourier inversion method is compared to a series evaluation method and the two methods are found to be complementary in that they perform well in different regions of the parameter space.     

Children's Perspectives on Their Relationships With Grandparents Following Parental Separation: A Longitudinal Study

Following parental separation, children's closeness to grandparents has been reported to be linked to their family situation and differences in adjustment. This relationship has not been investigated longitudinally. This study investigated children's relationships with grandparents over time in different family settings, and associations with intergenerational relationships. Data from 385 children, with longitudinal analyses on 140, were collected at two time points over a five‐year period. Associations between closeness of the child–grandparent relationship and adjustment were not found at the later time point. There was a mean drop in frequency of contact over time, but not in closeness. However, there was stability of individual differences in both frequency of contact and closeness; closeness to the maternal grandmother was particularly stable for children living with a single mother. Intergenerational links were found with the mother's own childhood experiences, particularly in single‐mother families. Following parental separation, the matrifocal bias in kinship patterns was accentuated.