On the Betfair Blog, Professor Leighton Vaughan Williams reports on PollyVote. Click here for the full article.
"PollyVote (www.pollyvote.com) is an election forecasting site which follows this principle of combining forecasts. By aggregating the vote-share snapshot contained in traditional opinion polls with a panel of American politics experts, a prediction market and a range of quantitative forecasting models, Polly provides a daily updated forecast of the share of the two-party vote that the Democratic and Republican Presidential candidates will obtain on polling day.
For their polling input they use a variation of the RealClearPolitics average and for their prediction market they use the Iowa Electronic Markets, a research and teaching-oriented marketplace which allows small bets on a range of contracts including the Presidential vote-share. The panel is made up of respected political scientists and pundits and the quantitative models (based on an analysis of the likely impact of variables ranging from unemployment and inflation to incumbency and wars) draw on an array of different methodologies. Each of these forecasts is assigned an equal 25% weight and in 2004 generated an almost spot-on forecast of the actual respective vote shares.
Is the RealClearPolitics average the best baseline to use for aggregating the polls? Is the Iowa market the best choice of prediction market? Is the chosen panel and the way its views are aggregated the best way to assimilate the combined knowledge of the political intelligentsia?
Is the range of forecasting models appropriate? Does the averaging of the four methodologies perform better than any one alternative forecasting methodology?
This debate will continue, and will be informed by how well Polly performs in forecasting the vote shares of the candidates. What we can already say for sure though, just two weeks out, is that if John McCain wins the election, this particular parrot will start to look very sick indeed."
