Material resources affect the levels of mortality. In cross-sectional relationships income has been found to be positively associated with survival, both within and between countries. Preston (1975, 1976), in particular, using cross-national data for three separate decades of the 20th century, showed that at any point in time there was a positive relationship between national income per capita and life expectancy. Other studies (e.g., those reviewed in Cochrane et al., 1980) have arrived at the same conclusion. Within countries, just as at the cross-national level, child mortality has been found to be inversely related to the economic status of the family, but the measure of economic status used has not always been the same. In the minority are studies of socioeconomic determinants of child mortality which have examined the association between economic status, measured by income, and child survival (Anker and Knowles, 1980; Carvajal and Burgess, 1978; Farah and Preston, 1982; Schultz, 1980; Tekce and Shorter, 1983).