Longitudinal panel studies are widely used in developmental science to address important research questions on human development across the lifespan. These studies, however, are often challenging to implement. They can be costly, time-consuming, and vulnerable to test--retest effects or high attrition over time. Planned missingness designs (PMDs),…

Existing data sets can be an efficient, powerful, and readily available resource for addressing questions about developmental science. Many of the available databases contain hundreds of variables of interest to developmental psychologists, track participants longitudinally, and have representative samples. In this article, the authors discuss the…

Longitudinal data analysis has long played a significant role in empirical research within the developmental sciences. The past decade has given rise to a host of new and exciting analytic methods for studying between-person differences in within-person change. These methods are broadly organized under the term "growth curve models." The…

Individuals with Down syndrome are predisposed to show a specific behavioural phenotype, or a pattern of strengths and challenges in functioning across different domains of development. It is argued that a developmental approach to researching the Down syndrome behavioural phenotype, including an examination of the dynamic process of the unfolding…

Researchers in the fields of cognitive and language development have made less use of large-scale longitudinal designs and of person-centered approaches to data analysis than have researchers in the fields of social and personality development. It is argued that differences among domains of developmental psychology in the research methods employed…