This book succeeds on several fronts. As Nate Silver says on its cover, it provides a definitive account of what mattered most in the 2012 presidential election. Further, it shows how political science analysis is completely relevant in understanding real-world politics and that political scientists are not students of the obvious. Such analysis requires masses of data used in systematic and theoretically informed ways—much more than saying “do the math” (p. 238). The book’s foils are the campaign and election accounts of journalists, insiders, and pundits who look to tell dramatic, event, and actor-centered stories that provide easy-to-understand explanations for their audiences. This more intuitive approach has been increasingly challenged in sports (e.g., Moneyball, 2003) and other realms by data analysts who attempt to make probabilistically better judgments (e.g., Nate Silver’s http://fivethirtyeight.com).

The mission of John Sides and his colleagues on the online site Monkey Cage (http://www.washingtonpost.com/blogs/monkey-cage) has been to demonstrate consistently the relevance of political science. Sides and Lynn Vavreck posted their initial analyses in real time to take on their foils, who by the end offered less relevant explanations for the way in which the primary and general elections ultimately played out. For the authors, it was data and political science know-how from decades of election studies that told the correct story in the end. Theorizing and empirics pointed the authors to the “fundamentals” that mattered. In the general election, that meant partisan base support and evaluations of government economic performance, short of any more salient performance issue. In the primaries, it meant support from party leaders who want the best candidate and how the winner demonstrated his superiority in funding and organizing his long campaign. The key for the authors is distinguishing longer-term from very short-term influences: day-to-day campaign activities, misstatements and other gaffes, and especially media coverage of these and other events that all have short half-lives.

Beyond data skills, one advantage that political scientists have over journalists, which would have been worth noting, is that they seek to get the final analysis right for an academic audience. While journalists and others writing for a market strive to be accurate, they are biased toward stories that attract audiences, which means fresh stories that focus on conflict, are dramatic, and stress the campaign horse race. Because they seek to find the daily “big story,” by the campaign’s end they have a different narrative about the election outcome. In contrast, Sides and Vavreck are able to see most of the short-term happenings as part of the ebb and flow, or “tug of war,” as they put it. In the general election, the effects of reports of day-to-day happenings cancel out.

The book moves through Mitt Romney’s triumph in getting the nomination to the analysis of the general election and its outcome. While the authors do not directly state it, their narrative, like those in the press and elsewhere, portray the American public and the electorate in particular in a positive light (as in works such as Benjamin I. Page and Robert Y. Shapiro, The Rational Public, 1992). Their opinions are not volatile, fickle, or capricious but change back and forth in ways that can be explained almost fully by new information about events and happenings during the campaign (though the quality or competence of these opinions may be open to debate).

Sides and Vavreck identify what has become the recurring pattern found in primary elections in the United States (since the presidential selection reforms of the 1970s): “discovery, scrutiny, and decline” (p. 7). That is, in the low-information context of primaries (in contrast to the general election where voter choices are stabilized by partisanship and familiarity with candidates), candidates are discovered through media coverage of initial successes, which results in increased support; this then leads to closer scrutiny of them, from which new information or what they may ineptly say or do causes their support to decline. All of the Republicans (Rick Perry, Herman Cain, Newt Gingrich, Rick Santorum) experienced this pattern, except for Romney. Each experienced a period of discovery as a credible candidate driven by changes in election poll standings, debates, or other campaign events. Each increased his positive visibility in the media, which led to closer press coverage that amplified misstatements and any uncovered past misdeeds, which then dampened the candidate’s support. What ultimately mattered was Romney’s strength in the “fundamentals” of funding, support from party leaders, and greater popularity in the largest and less conservative faction of the party.

In discussing the “dynamic equilibrium” of the general election, the authors report the short-term effects of the debates and the news coverage of other campaign occurrences on voter perceptions and choices. These included for Barack Obama the infamous first debate and for Romney his “47% speech.” They also describe any small but not decisive net effects of campaign ads in key states, as well as each candidate’s ground game as measured by numbers of local field offices. They refute journalists’ and pundits’ claims of a number of “decisive” factors, such as the “auto bailout” and the “war on women,” although they note that abortion attitudes did influence voters, as did racial resentment regarding Obama. Romney’s Mormonism had no effect. The authors estimated that during the campaign, the immigration issue contributed to Obama only “an additional half a point of vote share” among Latinos (p. 201), indicating that the issue’s influence was established before the general election. Readers will want to look closely at how particular temporary or ultimately small effects are estimated. In contrast, the fundamentals mattered more to Obama’s advantage: the Democrats’ edge on party identification and the campaign, making both partisanship and perceptions of improving economic conditions greater multivariate correlates. The campaign, then, mattered most in reinforcing partisan predispositions and priming the president’s positive economic performance.

Central to these analyses were substantial survey data on voter opinions and perceptions for cross-sectional, panel, and time-series analyses. For many important analyses, these included YouGov/Polimetrix surveys, totaling many thousands of respondents; for presidential approval trends: Gallup, CBS News/New York Times, and all publicly available data on pollster.com; and for other research questions, data from various polling organizations. In addition, media data—including the amount and directional content of coverage—were collected by General Sentiment and by the Project for Excellence in Journalism (PEJ). The sources for political ads were the Campaign Media Analysis Group (CMAG) and the Nielsen Company (in gross rating points). Other data included economic statistics and measures of consumer sentiment/perceptions of economic conditions. The authors’ analyses of these data are first rate, and the technical appendixes on the data and different modeling methods are clear and helpful, along with extensive endnotes for both data junkies and academics interested in causal inference. Yet given the book’s data emphasis, I was surprised not to find discussions of data quality.

The clarity and explicability of particular findings themselves may validate the data. But, in particular, given ongoing debates critiquing the current state of polling, some of the survey data warrant further discussion. While the use of YouGov/Polimetrix Internet surveys of self-selected panels is now accepted in political science journals and here in another major book (and is reviewed in Stephen Ansolabehere and Douglas Rivers, “Cooperative Survey Research,” Annual Review of Political Science 16 [2013]: 307–29), there is still much debate and controversy about the use of non-probability samples. Any problem in this regard is probably mitigated in The Gamble by the use of the data in multivariate analyses and to estimate changes over time (see the “Parallel Publics” chapter in Page and Shapiro’s The Rational Public), but nonprobability samples can be more problematic for point estimates of means or proportions. Other surveys cited at different points are those done by Rasmussen Reports, Public Policy Polling (PPP), and Survey USA, for which questions have been raised about biases in their automated Interactive Voice Response polls that may not call cellphones. Given the importance of drawing on such extensive data, future works should more transparently discuss issues of data quality.

As to “future works,” Sides and Vavreck’s success raises the question: Should others take a similar gamble in embarking on a book project in real time, with a fast turnaround, that draws on large-scale data and the best methods and insights that political science can offer? The authors have set a high bar and benefited from a now long history of research on voting and elections. They have shown that this kind of work can be done. The payoffs here for showcasing political science’s relevance to real-world politics are substantial.