Blackwell Reference Online

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The purpose of this chapter is to examine some of the central issues in research on aging. Most of the content of the chapter, although oriented towards the special issues facing researchers interested in the life stages of adulthood and old age, is equally relevant to the study of earlier life stages. These earlier stages are characterized by the rapid growth and differentiation of behaviors. By contrast, growth slows in young adulthood, and middle adulthood is characterized by long-lasting stability, while early old age shows decline occurring in some but not all individuals. In advanced old age, rapidly declining performance is then the norm. A perhaps even more important distinction is provided by the fact that studies of early development are typically conducted over short temporal periods and limited age ranges while studies of adulthood cover large age ranges and may extend across different historical eras. We begin this chapter by delineating the differences in conclusions that can be drawn from cross-sectional (or age-comparative designs) as contrasted to longitudinal (or within-group follow-up) research designs. Sequential research designs and related analytic strategies are then considered as possible ways to ameliorate the deficiencies of single time point cross-sectional and single-cohort longitudinal studies. Finally, we turn to an analysis of the threats to the internal ... log in or subscribe to read full text