Most of nine forecast models developed by political scientists predict a victory for Senator Barack Obama over Senator John McCain in the two-party contest for the popular vote in the 2008 presidential election. Obama is predicted to win an average of 52% of the vote with an 80% probability that he will gain more than half the total two-party popular vote.
Six out of the nine presidential election forecasts predict an Obama victory with popular vote totals ranging from 50.1% to 58.2%, while two predict a race too close to call and one predicts a narrow McCain victory. All of the predictions appear in an election-themed symposium in the October issue of PS: Political Science and Politics, a journal of the American Political Science Association (APSA). The forecasts, published in advance of presidential and mid-term elections, are available online at: www.apsanet.org/content_58382.cfm .
The forecasts are based on different combinations of statistical and historical data and differ in their complexity and how far in advance their predictions were made. The earliest forecast was made 294 days in advance while the latest was made 60 days before the election; however, all were made before the Wall Street financial crisis of the past few weeks. Together these forecasts use a range of approaches and indicators that are critical to understanding national electoral processes and the dynamics at work in U.S. presidential elections. Brief summaries of each are provided below:
-- In the earliest completed forecast made in January 2008, Helmut Norpoth's (Stony Brook University) "Primary Model" uses candidate support in presidential primaries to predict the general election two-party popular vote outcome. Norpoth's forecast makes Senator Obama the favorite by a razor-thin margin, predicting a 50.1% to 49.9% Obama victory, but also indicates only a 50% chance that Obama will gain a majority.
-- Using data from the second quarter of 2008, Brad Lockerbie (University of Georgia) employs two variables that are decided well in advance of the presidential conventions to forecast the presidential election: the amount of time a party has controlled the White House, and voters' expectations concerning their financial well-being over the course of the next year. Lockerbie predicts an impressive victory by Barack Obama, with John McCain gaining only 41.8% of the two-party popular vote en route to a loss in the 2008 presidential election.
-- Alan I. Abramowitz's (Emory University) "Time-for-Change" forecast model, completed in August 2008, is based on the assumption that a presidential election is fundamentally a referendum on the performance of the incumbent president. Abramowitz's model employs three variables: the growth rate of the economy during the second quarter of the election year, the incumbent president's approval rating at mid-year, and the length of time the incumbent president's party has controlled the White House. Abramowitz predicts Senator Barack Obama will receive 54.3% of the two-party popular vote in the 2008 presidential election.
-- Robert S. Erikson (Columbia University) and Christopher Wlezien's (Temple University) forecast model analyzes a combination of leading economic indicators and trial-heat polls from August 2008 to predict the election's final outcome. Their model predicts that Senator Obama will win 52.2% of the two-party popular vote, compared with 47.8% for Senator McCain.
-- Michael Lewis-Beck (University of Iowa) and Charles Tien (Hunter College and the Graduate Center, CUNY) "Jobs Model" weighs the sitting president's popularity and the actual number of jobs created or lost during his term with the powers of incumbency and economic growth. Unadjusted, it predicts that Senator Obama will win 56.57% of the two-party popular vote in what will amount to "the greatest incumbent popular vote loss on record from 1948." However, with refinements to factor in the impact of race, the Jobs Model predicts a final outcome where Senator Obama will win by a smaller margin, garnering 50.1% of the two-party vote and with a 50% chance that Obama will gain a majority. The forecast was made in August 2008.
-- Thomas M. Holbrook's (University of Wisconsin-Milwaukee) forecast model emphasizes presidential approval and the average level of satisfaction with personal finances in the summer before the presidential election. Completed in August 2008, his model predicts Barack Obama will garner 55.7% of the two-party presidential popular vote compared to John McCain's 44.3%.
-- Symposium editor James E. Campbell's (University at Buffalo, SUNY) "Trial Heat" forecast model integrates the incumbent's trial-heat Labor Day Gallup numbers and the real growth in the GDP in the second quarter of the election year. Completed in early September 2008, the Campbell model breaks with the other forecasts to predict that Senator McCain should be expected to receive 52.7% of the two-party popular vote.
-- Alfred G. Cuzan and Charles M. Bundrick (University of West Florida) use the "Fiscal Model" forecast and emphasize the relationship between the ratio of federal outlays to GDP and the share of the two-party vote going to incumbents. Completed in August 2008, their forecast predicts the Democratic candidate, Senator Barack Obama, will emerge victorious by a 52%-48% margin.
-- Carl Klarner (Indiana State University) employs a forecast model that focuses on broad range of state and district-level factors. Completed in late July 2008, his forecast predicts Senator Obama will obtain 53.0% of the popular vote and 346 electoral votes.
The 2008 presidential election is taking place in an extraordinary environment. The open-seat nature of the contest, the implications of President Bush's low approval ratings, Senator Obama's decision to forego public financing of his campaign, the effect of race on a contest featuring the first black candidate of a major party in U.S. history, the relative levels of party unity, and the impact of the Wall Street meltdown after these forecasts were produced all combine to make the outcome of the 2008 election unusually difficult to predict. Nevertheless, more of the forecasts predict an Obama victory than not, as the "median of these nine forecasts indicates that Senator McCain will receive 48% of the two-party popular vote," concludes symposium editor James Campbell.
Source: American Political Science Association
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