'In this lively and accessible book, Peter John has shared with readers a wealth of practical guidance that comes from years and years of field experimentation in political science and public policy. Every researcher should heed its advice before venturing into the field.' - Donald P. Green, Columbia University, USA'Experiments are revolutionizing what we think we know about many aspects of politics. This volume contributes nicely to this body of work by extending the focus to critical questions of public policy. This is a timely and important book.' - Costas Panagopoulos, Fordham University, USA