"Public policy is the process by which groups act collectively--everything from declaring war to installing stoplights. We study public policy in the hopes that we can do better. It is an audacious task. What activities are best handled by the market? How can we act in the face of scientific uncertainty? How can we make sense of the opinions of hundreds of millions of people? how can we evaluate trade-offs--economic growth versus environmental protection, for example? How can we even measure our success. This book is a toolkit for understanding the public-policy process and for making better public-policy decisions." [p.4] of cover.