Meta-Analysis

Meta-Analysis: Tool for Studying Life-Span Development

Meta-analysis is a particularly suitable method for the study of life-span human development in several ways. First, meta-analysis provides an [Page 1395]organized, systematic, and comprehensive approach to representing the findings of numerous complex and diverse individual studies and can have more scope, depth, and generality than any one primary study can provide. Second, aggregating the results of the multiple studies included in meta-analysis yields more statistically reliable estimates than individual studies alone. Furthermore, when there are differences in findings among studies, meta-analysis can identify the sources of those differences. For example, meta-analysis of studies of the etiology of particular diseases may reveal different etiologies associated with different subpopulations, or meta-analyses of social skills interventions may reveal that group-format programs are more effective than one-on-one programs covering the same content.

Research Questions Appropriate for Meta-Analysis

Three varieties of research questions are appropriate for meta-analysis in the area of life-span human development. One form of meta-analysis is well suited to questions about understanding the etiology and epidemiology of physical or mental health problems or identifying the factors that promote healthy development across the life span—meta-analyses of correlational relationships among biological, physical, cognitive, psychosocial, and emotional characteristics in humans and concurrent or later outcomes. Such meta-analyses can form the foundation for a risk-reduction/protection-enhancement approach to prevention by seeking to identify the significant predictors of a problem of interest or factors associated with positive outcomes that can be supported through intervention. They also can help identify individuals or groups in need of services or support and inform the development of interventions to ameliorate early problems and/or enhance selected protective factors with the expectation that this will prevent, or at least mitigate, problematic outcomes or improve positive ones.

A second category of research questions commonly explored with meta-analysis is that of intervention effectiveness or efficacy. Meta-analyses of intervention effects quantitatively summarize the empirical findings of a collection of studies on the same or similar interventions and can be applied to virtually any intervention delivered to individuals. For example, meta-analyses of this type can be applied to studies on the effects of medical treatments for disease and programs for promoting the cognitive or socioemotional development in children as well as assist in identifying treatments that may be harmful. Meta-analyses focusing on questions of intervention effectiveness are applicable across the life span because they can identify effective program strategies, reveal ineffective or harmful strategies, and illuminate the conditions under which programs may be more or less effective.

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