When researchers say they are interested in understanding normative stability and change, they mean typical or regular age-graded patterns of individual change and constancy. Because these goals are embedded within the larger meta-theory created by the lifespan perspective, they target two kinds of development: (1) patterns of normative change and stability and (2) patterns of differential change and stability. From a lifespan perspective, developmental science has three primary goals: to describe, explain, and optimize human development (Baltes, Reese, & Nesselroade, 1977 see Table 1.1). Research methods are tools that serve scientific ways of knowing, and their utility depends on the extent to which they can help researchers reach their scientific goals. Describe explanatory designs that extend these two and compensate for some of their limitations.Define the two explanatory designs, namely, naturalistic/correlational and experimental, show how they can be used in laboratory or field settings, and identify their strengths and limitations.Explain how sequential designs deal with the fatal flaws of the two basic designs, and how each design fits into a program of developmental research.Define the three descriptive designs, namely, cross-sectional, longitudinal, and sequential, and identify their fatal flaws/confounds, strengths and limitations.Compare and contrast the three goals of lifespan developmental science.

Sequential explanatory design