Group-level variance estimates of zero often arise when fitting multilevel or hierarchical
linear models, especially when the number of groups is small. For situations where zero …

Advancing the development, validation, and use of patient-reported outcome (PRO)
measures, Patient-Reported Outcomes: Measurement, Implementation and Interpretation …

Several authors have proposed the use of multilevel models to analyze data from single-
case designs. This article extends that work in 2 ways. First, examples are given of how to …

Reproduction in social organisms is shaped by numerous morphological, behavioural and
lifehistory traits such as body size, cooperative breeding and age of reproduction …

Objective To determine the effects of a 12week endurance exercise program on health,
disability, Vo2 max, and disease activity in a multicenter randomized controlled trial in …

The purpose of the study was to investigate the effect of changes on work motivation and the
effect of the changes on future mental well-being. This prospective study comprised 577 …

Several studies have shown that a woman's vaginal or axillary odors convey information on
her attractivity. Yet, whether such scents induce psychoneuroendocrinological changes in …

Objective The objectives of this study were to determine whether a measure of global self-
concept demonstrated longitudinal measurement invariance between adolescents aged 10 …

Background This article explores the association of people who inject drugs and their family
members in terms of mental health and family relations. The objective was to understand the …

Multivariate longitudinal data are common in medical, industrial, and social science
research. However, statistical analysis of such data in the current literature is restricted to …