Policy analysis is concerned with "who gets what" in politics and, more importantly, "why" and "what difference it makes." We are concerned not only with what policies governments pursue, but why governments pursue the policies they do, and what the consequences of these policies are.

Political science, like other scientific disciplines, has developed a number of concepts and models to help describe and explain political life. These models are not really competitive in the sense that any one could be judged as the "best." Each focuses on separate elements of politics, and each helps us understand different things about political life.

We begin with a brief description of eight analytic models in political science and the potential contribution of each to the study of public policy:

• Institutional model
• Process model
• Rational model
• Incremental model
• Group model
• Elite model
• Public choice model
• Game theory model

Most public policies are a combination of rational planning, incrementalism, competition among groups, elite preferences, public choice, political processes, and institutional influences. Throughout this volume we employ these models, both singly and in combination, to describe and explain public policy. However, certain chapters rely more on one model than another.

We attempt to describe and explain public policy by the use of these various analytic models. Readers are not only informed about public policy in a variety of key domestic policy areas; they are also encouraged to utilize these conceptual models in political science to explain the causes andconsequences of public policies in these areas. The policy areas studied are:

• Criminal justice
• Health and welfare
• Education
• Economic policy
• Taxation
• International trade and immigration
• Environmental protection
• Civil rights
• State and local spending and services
• National defense

Any of these policy areas might be studied by using more than one model. Frequently our selection of a particular analytic model to study a specific polity area was based as much on pedagogical considerations as on anything else. We simply wanted to demonstrate how political scientists employ analytic models. Once readers are familiar with the nature and uses of analytic models in political science, they may find it interesting to explore the utility of models other than the ones selected by the author in the explanation of particular policy outcomes. For example, we use an elitist model to discuss civil rights policy, but the reader may wish to view civil rights policy from the perspective of group theory. We employ public choice theory to discuss environmental policy, but the reader might prefer studying environmental problems from the perspective of the rational model.

Each chapter concludes with a series of propositions, which are derived from one or more analytic models and which attempt to summarize the policies discussed. The purpose of these summaries is to suggest the kinds of policy explanations that can be derived from analytic models and tie the policy material back to one or another of the models.

The new 10th Edition of Understanding Public Policy is a substantial revision. A much more extensive review of "The Policymaking Process" appears early in the text, with many new policy discussions: "Is Welfare Reform Working?"; "Does Crime Pay?"; "The Fed at Work"; "Replacing the Income Tax"; "Public Policy and Hispanic Americans"; "Public Policy and Gender Equality;" Public Policy and the Disabled"; "Federalism Revived?"; and "Terrorism and Unanticipated Threats to America."

This edition also updates controversial discussions such as: "Crime and Guns," "The Drug War," "RICO versus Liberty," "Social Security Reform," "Health Care Access and Costs," "Educational Reform and Parental Choice," "Tax Policy and the Special Interests," "Elite Gains from Trade," "Mass Losses from Trade," "Environmentalism versus Rational Public Choice," "Public Policy and Affirmative Action," "How Money and Power Flow to Washington," and "The Gulf War as a Case Study."

In short, this volume is not only an introduction to the study of public polity but also an introduction to the models political scientists use to describe and explain political life.

Thomas R. Dye
Florida State University