Neighbourhood inequality, neighbourhood affluence and population health.

While there is now considerable evidence that the neighbourhood income levels (poverty/affluence) exert an independent effect on health, there is little evidence that neighbourhood income inequality is consequential, net of individual-level socio-economic resources. We show that the usual explanation for the absence of an independent effect of neighbourhood inequality--the assumption of economic homogeneity at the neighbourhood level--cannot account for this result. The authors use hierarchical models that combine individual micro-data from Statistics Canada's 1996/97 National Population Health Survey (NPHS) with neighbourhood and city-level socio-economic characteristics from the 1996 Census of Canada to estimate the effects of neighbourhood affluence and income inequality on self-reported health status. The findings indicate that the negative "ecological" correlation between average neighbourhood health and neighbourhood income inequality is the result not only of compositional differences among individuals but also of contextual neighbourhood effects associated with low and high inequality neighbourhoods.