Whether a Sociologist, Economist, Psychologist or Simply a Skilled Evaluator Lessons from Evaluation Practice in the United

Over the past 35 years, evaluation in the United States has moved from a tool of the academic disciplines – economics, sociology and psychology – to a booming profession. This new profession taps the theories, research tools and analytic methods of the disciplines to address important social and economic concerns facing businesses, schools, communities and policy makers. Four factors have contributed significantly to the emergence and growth of the profession: (1) a major expansion of public policy and the demand for public accountability; (2) a commitment to practical relevance of research by scholars and technicians; (3) a strengthening of evaluation methodologies and technologies; and (4) improve-ments in communication skills and strategies. Social experiments are at the heart of the policy evaluation industry in the United States. However, the growth and professionalization of evaluation have resulted in large part from broadening the focus of evaluations to encompass more complex questions than can be addressed through classical social experi-ments alone. Classical experiments, whereby subjects are randomly assigned to different policy regimes or policy experiences, can be extremely powerful for answering the ‘what if ’ questions that are central to public policy deliberations. What if we offered wage subsidies to low-income workers? What if we required adults on public assistance to perform community service jobs? What if we allowed parents to choose the public schools their children attend? Or what if we changed the skills requirements for school teachers