Contained in this volume are the edited and refereed papers which were presented at a conference held at Nuffield College, Oxford in May 1987. The papers, which represent the recent research of a group of eminent economists, reflect the variety and scope of modern economic analysis. New results are presented in econometric estimation, the theory of aggregation, poverty measurement and the general theory of measurement in economics. The volume is distinguished by the inclusion of the discussion which occurred as each paper was presented, so capturing the interaction and exchange of ideas that characterised the conference.