Nigar Hashimzade is a Professor of Economics at Durham University, a Research Fellow at the Institute for Fiscal Studies and the Tax Administration Research Centre, and a managing editor of the Journal of Tax Administration. She obtained her PhD in Economics from Cornell University in 2003. Prior to Durham University she held academic positions at Economics departments in Exeter and Reading. She has published research articles in economic theory and econometric theory. Her current research is focussed primarily on various issues in applied microeconomic theory. Gareth Myles is Professor of Economics at the University of Exeter, a Research Fellow at the Institute for Fiscal Studies and at CESifo, and Director of the Tax Administration Research Centre. He obtained his D.Phil. (1987) from the University of Oxford under the supervision of Professor Sir James Mirrlees. His first academic position was at the University of Warwick and he moved to the University of Exeter in 1992. His major research interest is in public economics and his publications include Public Economics (1995), Intermediate Public Economics (2013) and numerous papers in International Tax and Public Finance, the Journal of Public Economic Theory, and the Journal of Public Economics. He is an Associate Editor of the Journal of Public Economic Theory and a member of the Mirrlees Review. He is an Academic Adviser to HM Treasury and HM Revenue and Customs, and has also provided economic advice to international bodies including the European Commission and the OECD. John Black worked on previous editions of this dictionary and was a Fellow and Tutor in Economics at Merton College, Oxford and then Professor of Economic Theory at the University of Exeter. His many publications include The Economics of Modern Britain, Essential Mathematics for Economics (with J.F. Bradley), and Housing Policy and Finance (with D.C. Stafford). He is now an Emeritus Professor of the University of Exeter.