Those who seek to accurately gauge public opinion must first ask themselves: Why are certain opinions highly volatile while others are relatively fixed? Why are some surveys affected by question wording or communicative medium (e.g., telephone) while others seem immune? In Hard Choices, Easy Answers, R. Michael Alvarez and John Brehm develop a new theory of response variability that, by reconciling the strengths and weaknesses of the standard approaches, will help pollsters and scholars alike better resolve such perennial problems. Working within the context of U.S. public opinion, they contend that the answers Americans give rest on a variegated structure of political predispositions--diverse but widely shared values, beliefs, expectations, and evaluations. Alvarez and Brehm argue that respondents deploy what they know about politics (often little) to think in terms of what they value and believe. Working with sophisticated statistical models, they offer a unique analysis of not just what a respondent is likely to choose, but also how variable those choices would be under differing circumstances. American public opinion can be characterized in one of three forms of variability, conclude the authors: ambivalence, equivocation, and uncertainty. Respondents are sometimes ambivalent, as in attitudes toward abortion or euthanasia. They are often equivocal, as in views about the scope of government. But most often, they are uncertain, sure of what they value, but unsure how to use those values in political choices.