Fonti di distorsione nella misura delle disuguaglianze di salute: la validazione, il confronto temporale e spaziale, l’aggiustamento per altre covariate, il bias ecologico - The use of socio-economic indicators in the analysis of health outcomes is not straightforward because those conditions act in a mediated and indirect way through the adoption of life styles, the characteristics of job or the capabilities of utilizing the opportunity of wellbeing offered by the modern health systems. Validity analyses of the national deprivation index based on indicators derived from national Census are summarized. Spatial and temporal stability of the association between deprivation and mortality are reviewed and Italian examples presented. Mutual standardization bias and ecological fallacy when using census tract data are also illustrated with original data based on longitudinal census cohorts studies. Keywords: material deprivation, mortality, validity, ecological fallacy, epidemiology, ecological bias. Parole chiave: deprivazione materiale, mortalità, validazione, distorsione ecologica, epidemiologia, bias ecologico.