Prof Clarke previously spent six years engaged in health economic research at the University of Oxford. His research in Oxford focused on the economic analysis of the United Kingdom Prospective Diabetes Study (UKPDS) – a landmark trial of policies to improve the management of people with Type 2 diabetes.
His health economic research interests include developing methods to value the benefits of improving access to health care, health inequalities and the use of simulation models in health economic evaluation. He has also undertaken policy relevant research for the World Bank, OECD, AusAID and DoHA.

He has over 80 peered review publications and has recently contributed to books on cost-effectiveness analysis and cost-benefit analysis published by Oxford University Press.