Purpose: The purpose of this study was to investigate the characteristics of missing physical activity (PA) data of children and youth. Method: PA data from the Chinese City Children and Youth Physical Activity Study ("N" = 2,758; 1,438 boys and 1,320 girls; aged 9-17 years old) were used for the study. After the data were sorted by the…

Developmental differences in categorization in a communication situation were investigated among 16 adult women and 16 nine-year-old children who instructed 7-year-old children in either the organization of groceries in a mock kitchen (home task) or the sorting of photographs of common objects into compartments (school task). In both tasks, the 18…

Two experiments which investigated the young child's ability to deal with multiplicative classes and relations (considered behavioral indices of concrete operations thought) in double series and cross class matrices are described and discussed. In the initial study, 160 children from preschool through grade 2 received six matrix subtasks…

Argues that rank order correlations may not be ubiquitously suitable for assessing the relations between children's behavior or characteristics at one age or in one situation, and those shown later or in another context. (HOD)