Introduction: evaluation in analytic theory and political practice.

The development of professional policy analysis was driven by a desire to apply "science" to policy decisions, but the vision of apolitical policy analysis is as unattainable today as it was at the inception of the field. While there is powerful evidence that schemes to "get around" politics are futile, they never seem to lose their popularity. The contemporary enthusiasm for health technology assessment and comparative-effectiveness research extends these efforts to find technical, bureaucratic fixes to the problem of health care costs. As the benefits and costs of health care continue to grow, so too will the search for analytic evidence and insights. It is important to recognize that the goal of these efforts should not be to eliminate but rather to enrich political deliberations that govern what societies pay for and get from their health care systems.