Policy Analysis by Design examines the approaches to public policy taken by those who try to teach it, write about it, and influence it through major analysis.& Bobrow and Dryzek systematically compare the five major contending analytical frames of reference: welfare economics, public choice, social structure, information processing, and political philosophy.& The workings of each frame are illustrated by means of a common, if imaginary, policy case - air pollution in the hypothetical Smoke Valley.