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"Well written and clear, with entertaining and sometimes surprising examples, this book of excellent scholarship is designed for those who don't know any statistics and need to be walked through it. The author is both patient and painstaking, popularizing statistical thinking in a way that makes it available to a wide audience and communicating interesting social science at the same time. He puts things in a striking light that should communicate to an audience that is not otherwise served."--John Ferejohn, Stanford University
"Predicting Presidential Elections and Other Things is a captivating account of how social scientists attempt to predict future quantitative events using past trends and quantitative relationships."--American Journal of Economics and Sociology

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What do the following events have in common? In 2000, the election between George W. Bush and Al Gore was a virtual tie. The 1989 and 1990 vintages have turned out to be two of the best ever for Bordeaux wines. In 2001, the Federal Reserve lowered the interest rate eleven times. The decade of the 1970s was one of the worst on record for U.S. inflation. In 2001, the author of this book, at age 59, ran a marathon in 3 hours and 30 minutes, but should have been able to do it in 3 hours and 15 minutes.
This book shows clearly and simply how these diverse events can be explained by using the tools of the social sciences and statistics. It moves from a discussion of formulating theories about real world phenomena to lessons on how to analyze data, test theories, and make predictions. Through the use of a rich array of examples, the book demonstrates the power and range of social science and statistical methods.
In addition to "big" topics--presidential elections, Federal Reserve behavior, and inflation--and "not quite so big" topics--wine quality--the book takes on questions of more direct, personal interest. Who of your friends is most likely to have an extramarital affair? How important is class attendance for academic performance in college? How fast can you expect to run a race or perform some physical task at age 55, given your time at age 30? (In other words, how fast are you slowing down?) As the author works his way through an incredibly broad range of questions and topics, demonstrating the usefulness of statistical theory and method, he gives the reader a new way of thinking about many age-old concerns in public and private life.

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PREDICTING PRESIDENTIAL ELECTIONS AND OTHER THINGS

Stanford University Press

Contents

Preface...................................................ixIntroduction: What This Book Is About.....................11 It's the Economy, Stupid................................62 The Tools in Seven Easy Lessons.........................183 Presidential Elections..................................464 Congressional Elections.................................685 Extramarital Affairs....................................856 Wine Quality............................................1017 College Grades and Class Attendance.....................1158 Marathon Times..........................................1239 Aging and Baseball......................................14110 Predicting College Football Games......................16011 Interest Rates.........................................17112 Inflation..............................................18913 More Things............................................202Chapter Notes.............................................205Glossary..................................................209Poetry Credits............................................211Index.....................................................213

Chapter One

Election night at midnight: Boy Bryan's defeat. Defeat of western silver. Defeat of the wheat. Victory of letterfiles And plutocrats in miles With dollar signs upon their coats, Diamond watchchains on their vests and spats on their feet. Vachel Lindsay, from Bryan, Bryan, Bryan, Bryan

A common pastime in the United States every four years is predicting presidential elections. Polls are taken almost daily in the year of an election, and there are Web sites that allow betting on elections.

Some of the more interesting footnotes to presidential elections concern large errors that were made in predicting who would win. In 1936, the Literary Digest predicted a victory for Republican Alfred Landon over Democrat Franklin Roosevelt by a fairly large margin, when in fact Roosevelt won election to a second term by a landslide. The Literary Digest polled more than 2 million people, so the sample size was huge, but the sample was selected from telephone directories and automobile registrations, which overrepresented wealthy and urban voters, more of whom supported Landon. In addition, the response rate was higher for voters who supported Landon. The Literary Digest never really recovered from this error, and it ceased publication in 1938.

Another famous error was made by the Chicago Tribune in 1948, when it ran the headline "Dewey Wins." After it became clear that Thomas Dewey had lost, a smiling Harry Truman was photographed holding up the headline.

A more recent large error was made in June 1988, when most polls were predicting Michael Dukakis beating George Bush by about 17 percentage points. A few weeks later, the polls began predicting a Bush victory, which turned out to be correct.

While interesting in their own right, polls are limited in helping us understand what motivates people to vote the way they do. Most polls simply ask people their voting plans, not how or why they arrived at these plans. We must go beyond simple polling results to learn about the factors that influence voting behavior. This is where tools of the social sciences and statistics can be of help.

A Theory Of Voting Behavior

To examine the question of why people vote the way they do, we begin with a theory. Consider a person entering a voting booth and deciding which lever to pull for president. Some people are dyed-in-the-wool Republicans and always vote for the Republican candidate. Conversely, others are dyed-in-the-wool Democrats and always vote Democratic. For some, one issue, such as abortion or gun control, dominates all others, and they always vote for the candidate on their side of the issue. For these people, there is not much to explain. One could try to explain why someone became a staunch Republican or Democrat or focused on only one issue, but this is not the main concern here. Of concern here are all the other voters, whom we will call swing voters. Swing voters are those without strong ideological ties and whose views about which party to vote for may change from election to election. For example, Missouri is considered a swing state (that is, a state with many swing voters). It sometimes votes Democratic and sometimes Republican. Massachusetts, on the other hand, almost always votes Democratic, regardless of the state of the economy or anything else, and Idaho almost always votes Republican. The percentage of swing voters in these two states is much smaller than the percentage in Missouri.

What do swing voters think about when they enter the booth? One theory is that swing voters think about how well off financially they expect to be in the future under each candidate and vote for the candidate under whom they expect to be better off. If they expect that their financial situation will be better off under the Democratic candidate, they vote for him or her; otherwise, they vote for the Republican candidate. This is the theory that people "vote their pocketbooks." The theory need not pertain to all voters, but to be of quantitative interest, it must pertain to a fairly large number.

The Clinton presidential campaign in 1992 seemed aware that there may be something to this theory. In campaign headquarters in Little Rock, Arkansas, James Carville hung up a sign that said, "It's the Economy, Stupid"—hence the title of this chapter.

The theory as presented so far is hard to test because we do not generally observe voters' expectations of their future well-being. We must add to the theory an assumption about what influences these expectations. We will assume that the recent performance of the economy at the time of the election influences voters' expectations of their own future well-being. If the economy has been doing well, voters take this as a positive sign about their future well-being under the incumbent party. Conversely, if the economy has been doing poorly, voters take this as a negative sign. The theory and this assumption then imply that when the economy is doing well, voters tend to vote for the incumbent party, and when the economy is doing poorly, they tend to vote for the opposition party.

We now have something that can be tested. Does the incumbent party tend to do well when the economy is good and poorly when the economy is bad? Let's begin by taking as the measure of how the economy is doing the growth rate of output per person (real per capita gross domestic product [GDP]) in the year of the election. Let's also use as the measure of how well the incumbent party does in an election the percentage of the two-party vote that it receives. For example, in 1996, the growth rate was 3.3 percent, and the incumbent party candidate (Bill Clinton) got 54.7 percent of the combined Democratic and Republican vote (and won—over Bob Dole). In 2008, the growth rate was –2.3 percent, and the incumbent party candidate (John McCain) got 46.3 percent of the combined two-party vote (and lost—to Barack Obama). (The reasons for using the two-party vote will be explained later.)

Figure 1-1 is a graph of the incumbent party vote share plotted against the growth rate for the 24 elections between 1916 and 2008....