Sunday, September 4, 2016

From the Washington Post: Election forecasters try to bring some order to a chaotic political year

For a handful of political scientists, presidential elections can be forecast with a properly designed algorithm. The debate is over what algorithm works best.

- Click here for the article.
One model, by Robert Erikson of Columbia University and Chris Wlezien of the University of Texas, points to Clinton winning with 52 percent of the two-party popular vote. (Actual vote percentages for Clinton and Trump will be lower because of the presence of Libertarian Gary Johnson and the Green Party’s Jill Stein on the ballot.) That model combines post-convention polls with the results from the index of leading economic indicators.

Michael Lewis-Beck of the University of Iowa and Charles Tien of Hunter College also see a Clinton victory, with just 51 percent of the two-party popular vote. Tien said that translates to a narrow electoral college majority for Clinton of 274 votes.

Andreas Graefe of LMU Munich and J. Scott Armstrong of the Wharton School at the University of Pennsylvania cite four different models, all of which point to a victory by Clinton larger than some of the other forecasts.

One outlier is Helmut Norpoth of Stony Brook University. His model takes into account sentiment for a change in parties, but most important, and unusual, is his reliance on performance by the major-party candidates during the early presidential primaries, in this case New Hampshire and South Carolina. On that basis, he predicted last spring that Trump would win the election and said the prediction came with an 87 percent certainty.

When I spoke with Norpoth a few days ago, he was admittedly nervous. “I do worry. . . . I’m clearly sort of the odd man out,” he said. But, he added, “it’s not a foregone conclusion that he’s [Trump] going down the tubes.”

Alan Abramowitz of Emory University uses what he calls a Time for Change Forecasting Model. His model does not rely on polling data but instead takes into account the incumbent president’s approval rating at midyear, the growth rate of real gross domestic product in the second quarter of the election year and whether the incumbent president’s party has held the White House for one term or more than a term.

On that basis, his model predicts a narrow victory for Trump. But Abramowitz also suggests that Trump could underperform. “A model like mine that relies entirely on fundamentals is likely to miss the result because Trump is such an atypical candidate,” he said.

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