Investigating neighborhood and area effects on health

The past few years have witnessed an explosion of interest in neighborhood or area effects on health. Several types of empiric studies have been used to examine possible area or neighborhood effects, including ecologic studie s relating area characteristics to morbidity and mortality rates, contextua l and multilevel analyses relating area socioeconomic context to health out comes, and studies comparing small numbers of well-defined neighborhoods. Strengthening inferences regarding the presence and magnitude of neighborho od effects will require addressing a series of conceptual and methodologica l issues. Many of these issues relate to the need to develop theory and spe cific hypotheses on the processes through which neighborhood and individual factors may jointly influence specific health outcomes. Important challeng es include defining neighborhoods or relevant geographic areas, identifying significant area or neighborhood characteristics, specifying the role of i ndividual-level variables, incorporating life-course and longitudinal dimen sions, combining a variety of research designs, and avoiding reductionism i n the way in which "neighborhood" factors are incorporated into models of d isease causation and quantitative analyses.