title: A Monte Carlo method to estimate the confidence intervals for the concentration index using aggregated population register data.
abstract: In this paper, we introduce several statistical methods to evaluate the uncertainty in the concentration index (C) for measuring socioeconomic equality in health and health care using aggregated total population register data. TheCis a widely used index when measuring socioeconomic inequality, but previous studies have mainly focused on developing statistical inference for sampled data from population surveys. While data from large population-based or national registers provide complete coverage, registration comprises several sources of error. We simulate confidence intervals for theCwith different Monte Carlo approaches, which take into account the nature of the population data. As an empirical example, we have an extensive dataset from the Finnish cause-of-death register on mortality amenable to health care interventions between 1996 and 2008. Amenable mortality has been often used as a tool to capture the effectiveness of health care. Thus, inequality in amenable mortality provides evidence on weaknesses in health care performance between socioeconomic groups. Our study shows using several approaches with different parametric assumptions that previously introduced methods to estimate the uncertainty of theCfor sampled data are too conservative for aggregated population register data. Consequently, we recommend that inequality indices based on the register data should be presented together with an approximation of the uncertainty and suggest using a simulation approach we propose. The approach can also be adapted to other measures of equality in health.
authors.affiliation: The Social and Health Systems Research Unit, The Department of Health and Social Care Systems, The National Institute for Health and Welfare (THL), P.O. Box 30, 00271 Helsinki, Finland.
authors.forename: Sonja
authors.initials: S
authors.lastname: Lumme
authors.affiliation: Department of Social Research, Faculty of Social Sciences, Centre for Quantitative Methods, University of Helsinki, P.O. Box 33, 00014 Helsinki, Finland.
authors.forename: Reijo
authors.initials: R
authors.lastname: Sund
authors.affiliation: MRC/CSO Social and Public Health Sciences Unit, University of Glasgow, 200 Renfield Street, Glasgow, G2 3QB Scotland, UK.
authors.forename: Alastair H
authors.initials: AH
authors.lastname: Leyland
authors.affiliation: The Social and Health Systems Research Unit, The Department of Health and Social Care Systems, The National Institute for Health and Welfare (THL), P.O. Box 30, 00271 Helsinki, Finland ; School of Health Sciences, University of Tampere, Tampere, 33014 Finland.
authors.forename: Ilmo
authors.initials: I
authors.lastname: Keskimäki
keywords: Amenable mortality; Concentration index; Confidence interval; Equality; Health and health care register data; Monte Carlo simulation