Can outcomes be predicted before even a single vote is cast?

By Christian Grose, assistant professor of government

Lawrence Today magazine, Fall 2004

Christian Grose photoHow can we predict the outcome of a presidential election before it even occurs?

In recent decades, political scientists and economists have been able to forecast, with relative precision, the exact vote percentage that an incumbent presidential candidate or the candidate of the incumbent’s party will receive, based on past election results.

By using statistical models to examine the impact of theoretically relevant economic and political variables on past presidential election outcomes, scholars have, for the most part, been able to predict the winner with quite a bit of accuracy — although there have been notable embarrassments.

Forecasting elections is part science and part art. One of Lawrence’s key contributions to the field of government and political science was Professor William H. Riker, a member of the Lawrence faculty from 1948 to 1962, who reshaped the field to be more scientific in nature. Specifically, he was a proponent of pairing theory with rigorous analysis to examine predictable patterns observed in politics.

The “science” of forecasting elections lies in knowing that there are reliable patterns of behavior on the part of both voters and candidates. Voters are usually predictable, and there are certain factors that regularly explain electoral outcomes. In an election with two major-party candidates, the candidates will also behave predictably, taking stances and engaging in campaign activities designed to give them the most complete advantage. These activities often have the effect of canceling each other out. Thus, at the end of the election, even though the day-to-day battles of the campaign are important, other factors, some outside of their control, are likely to contribute to the election’s final outcome.

The “art” part of forecasting elections has to do with determining just what those “other factors” are and tweaking the statistical models to lead to the best prediction. Based upon scholars’ statistical models, I will detail four key factors that are able to predict which presidential candidate is likely to win. This will provide a guide for what you might expect this November in the contest between George W. Bush and John Kerry.

There are four key indicators that work well in forecasting presidential elections:
     (1)  economic growth,
     (2)  presidential approval,
     (3)  the extent of U.S. international involvement, and
     (4)  the comparative political experience of the two major-party candidates.

It is important to note that these models predict only the two-party popular vote between Republicans and Democrats. Of course, as we know from both the 2000 election and from the work of the late Professor Lawrence Longley, a Lawrence government professor from 1965 to 2002, the design of our presidential election system, with its electoral college, can occasionally lead to a popular-vote winner who is not the electoral-vote winner. As these forecasting models are based on aggregate national data, the prediction is for the two-party popular vote. In addition, only the two-party vote is predicted for the sake of simplicity.

Factor 1: Economic growth rate
Of the four factors, two have since World War II been the best predictors: (1) the economic growth rate (the second-quarter Gross Domestic Product growth rate) between six and nine months before the November election and (2) the presidential approval rating between four and six months before the November election.

Even more than (3) the extent of U.S. international involvement and (4) the candidates’ political experience, these are the most critical indicators, although international involvement and political experience are also relevant.

If the economic growth rate is strong in the second quarter of 2004 and the incumbent’s approval numbers are around 50 or higher, then Bush is in a strong position. If the economic growth rate in the second quarter is relatively low or Bush’s approval ratings are hovering in the mid- to low-40s, Kerry is in a strong position for victory.

The simplest forecasting model posits that second-quarter growth in the gross domestic product (GDP) affects the vote received by the candidate of the president’s party in November. Forecasters take the second-quarter GDP in the year before the election and in the year of the election and examine the change from one year to the next (2003 second quarter compared to 2004 second quarter).

Political scientists James Campbell, Tom Rice, and Michael-Lewis Beck, among others, use second-quarter growth rates in their models of election forecasting. Ray Fair, a Yale economist, uses first-, second-, and third-quarter GDP growth in his. The second-quarter growth rate is the best indicator because there is a time lag for positive or negative economic growth to trickle down to the average voter. Economic growth in the second quarter is likely to have reached the pocketbooks of Americans in tangible ways before ballots are cast in November.

More specifically, political scientist Randall Jones, Jr., has summarized a variety of forecasting models and notes the levels at which economic growth spells trouble or signals likely victory for an incumbent president or candidate from an incumbent president’s party. If GDP growth is 2.6 or higher, the incumbent party’s candidate is likely to win the popular vote. If GDP growth is 1.5 or lower, the incumbent party’s candidate is likely to lose the popular vote. And if GDP growth is between 1.6 and 2.5, the prediction is not clear.

This factor has done the best job in correctly predicting the winner of every presidential election since 1956 except one (based on a second-quarter growth rate of 6.5 percent in 1968, Hubert Humphrey, and not Richard Nixon, should have won the presidency). However, in all other years, this predictor worked. For instance, in 1980, economic growth in the second quarter was at an abysmal -10.2, and Ronald Reagan defeated incumbent Jimmy Carter. Four years later, in 1996, the economic growth rate was 5.3 percent, and Ronald Reagan sailed to reelection. Based solely on economic growth, which was 3.0 percent in the second quarter of 2004, George W. Bush appears to be at an advantage for this election.

Factor 2: Presidential approval rating
Economic growth is not the only key explanatory factor in predicting elections. Presidential approval approximately four to six months before the election is a critical predictor of the final outcome.

While a handful of truly “swing” voters do not decide until just before Election Day, most undecided voters or leaners solidify their views in favor or against the president and the candidates in mid-summer. If the incumbent president’s approval rating is 50 percent or greater, then the candidate of the party of the president is in strong shape to win the election in November. However, if this approval rating falls below 50, especially if it is significantly below 50, then it is likely that the candidate of the president’s party will lose the popular two-party vote.

The president’s approval rating is measured by the percentage of Americans who respond that they approve of the president’s job performance when asked the following question: “Do you approve or disapprove of the job George W. Bush is doing as president?”

Thus, the formation of public opinion regarding the job that Bush is doing as president is critical for his reelection chances. Bush’s approval ratings have been relatively erratic (at press time), and this does not provide the clearest prediction of his likelihood of winning. The most successful candidates in post-WWII elections have typically been held in high esteem by the electorate in the summer before Election Day. For instance, Ronald Reagan’s approval rating hovered in the mid-to-high 50s through the summer of 1984, and never dropped below 52 percent during this period. In contrast, when George H.W. Bush sought reelection in 1992, his approval rating was below 40 percent throughout most of the summer months, sealing his fate in November.

According to a Roper Center poll taken at the end of July, George W. Bush’s approval rating was 47 percent.

Factor 3: International involvement
The third key factor in forecasting presidential election outcomes is the extent of U.S. involvement in overseas affairs.

In the wake of September 11, 2001, when America found itself under terrorist attack, the political dynamics of Washington — and perhaps presidential elections — changed.

Generally, during times of foreign-policy crises, Americans “rally around the flag” and their president. Specifically, some political scientists and economists who statistically model election outcomes suggest that when U.S. involvement in foreign affairs is high, the incumbent president or the candidate of the president’s party is more likely to win. Some measure this by the number of troops deployed overseas, while others simply consider the number of recent U.S. international conflicts.

This indicator would seem to suggest that President Bush’s reelection chances are enhanced by the relatively high U.S. involvement overseas in the multiple venues of Afghanistan and Iraq following the 9-11 attacks.

However, Kerry fans should take note. The one year in which the economic-growth predictions mentioned earlier were unsuccessful was in 1968. Hubert Humphrey, the Democratic candidate, was predicted to win simply based on an economic growth rate of 6.5 percent and the fact that the incumbent president, Lyndon Johnson, was also a Democrat. However, the U.S. was involved heavily in the Vietnam conflict at this point, which was growing more unpopular as each day progressed closer toward November.

It is mere speculation at this point, but 2004 may be an anomalous case where the extent of international involvement does not necessarily help the incumbent president. If Americans ultimately determine that extensive involvement in Iraq was not a good idea, then this is likely to be reflected in Bush’s approval rating, the second predictive factor. However, if recent history — except 1968 — is our guide, then the high level of U.S. involvement in overseas affairs will pay off electorally for President Bush in November.

Factor 4: Candidates’ political experience
The fourth and final factor that is useful in predicting presidential electoral outcomes is the relative experience of the two major-party candidates.

Typically, incumbent presidents have a slight advantage here, though most candidates have extensive experience in government if they become a major party’s nominee. In 2004, since Kerry has nearly two decades of experience in the U.S. Senate and Bush obviously has experience as president, there is not a huge imbalance on this factor and it is unlikely to be of consequence. Generally, though, if there is a serious imbalance in experience, the more experienced candidate does better.

What does this all mean?
While there are clear patterns that are able to help us predict the likely winner in a presidential election before voting occurs, do not sit at home on Election Day. It is still normatively important to participate in democracy and cast your vote.

Also, the practice of forecasting elections is similar to the ability of meteorologists to predict the weather with a reasonable degree of accuracy. While they often predict correctly, sometimes the forecast is for sun, and it actually ends up raining. Take heart: if you do not think these indicators line up for your candidate of choice in the 2004 November elections, then hope for rain! Or, if they do line up for your candidate, remember that even forecasters cannot be 100 percent correct 100 percent of the time. Nevertheless, by harnessing the predictive power of observable patterns in repeated presidential elections, we are able to make an educated prediction going beyond mere speculation.


Christian Grose, who joined the Lawrence faculty in 2002, is interested in American government and politics, with specialties in congressional representation, parties, elections, voting behavior and public opinion, voting rights, racial politics, research methods, and the empirical testing of formal models. He holds a bachelor’s degree from Duke University and a doctorate from the University of Rochester. He is the 2004 recipient of the American Political Science Association’s Carl Albert Dissertation Award for the best doctoral dissertation in the area of legislative studies. The dissertation, “Beyond the Vote: A Theory of Black Representation in Congress,” examines the effect of electoral structures and the election of black legislators on the representation of black constituencies in Congress. Professor Grose is the first faculty member at a liberal arts college to receive the award.