Defining the "urban" in urbanization and health: a factor analysis approach.

Urban environments have been linked to a range of human health issues, and as the pace of urbanization accelerates, new challenges arise to characterize these environments, and to understand their positive and negative implications for health. We seek to contribute to future studies of urbanization and health by exploring multiple definitions of urbanicity in the Philippines, using data from an ongoing, longitudinal study. We use factor analysis to identify meaningful clusters of household- and community-level variables, and to generate factor scores that summarize each household's position with respect to access to infrastructure and health services, and level of affluence. Factor scores are considered for 1983 and 1994 to assess the type and pace of change that has occurred in the Philippines, and scores are compared across urban and rural areas, and across six different settlement types, to explore household- and community-level markers of urbanicity. This analysis demonstrates the heterogeneity of environments within urban and rural areas, and emphasizes the need for a finer level of investigation in future studies of urbanization and health.