title: conindex: Estimation of concentration indices.
abstract: Concentration indices are frequently used to measure inequality in one variable over the distribution of another. Most commonly, they are applied to the measurement of socioeconomic-related inequality in health. We introduce a user-written Stata commandconindexwhich provides point estimates and standard errors of a range of concentration indices. The command also graphs concentration curves (and Lorenz curves) and performs statistical inference for the comparison of inequality between groups. The article offers an accessible introduction to the various concentration indices that have been proposed to suit different measurement scales and ethical responses to inequality. The command's capabilities and syntax are demonstrated through analysis of wealth-related inequality in health and healthcare in Cambodia.
authors.affiliation: Erasmus School of Economics Erasmus University Rotterdam, the Netherlands Tinbergen Institute, the Netherlands and University of Macedonia, Greece.
authors.forename: Owen
authors.initials: O
authors.lastname: O'Donnell
authors.affiliation: Department of Health Services Research and Policy-London School of Hygiene and Tropical Medicine, UK stephen.oneill@lshtni.ac.uk.
authors.forename: Stephen
authors.initials: S
authors.lastname: O'Neill
authors.affiliation: Erasmus School of Economics Erasmus University Rotterdam, the Netherlands and Tinbergen Institute, the Netherlands.
authors.forename: Tom
authors.initials: T
authors.lastname: Van Ourti
authors.affiliation: Division of Health Services Research and Management School of Health Sciences and City Health Economics Centre City University London, UK.
authors.forename: Brendan
authors.initials: B
authors.lastname: Walsh
keywords: concentration index; health; healthcare; inequality; rank-dependent indices