Tuesday, April 22, 2008

Forecast for PA

So I'm sitting here wondering how things will turn out tonight in Pennsylvania and it occurs to me that the wealth of data at Pollster.com might provide some insights. To that end, I've developed a simple little forecasting model for the Pennsylvania primary based on the relationship between Charles Franklin's final, pre-election estimates of poll standing (in states where there were enough polls to generate estimates, and excluding Florida) and actual votes cast. As the figure below illustrates, there have been a few hiccups along the way but the actual results have tracked fairly well with the final poll estimates:
Adding a control variable for whether support for whether Edwards was in the final poll estimate (the negative coefficient suggests that Clinton did about four points worse than expected in the polls when Edwards was in the mix), we get the following model for forecasting Clinton's share of the two-candidate vote in Pennsylvania:

Plugging in the final estimate of her share of the two-Candidate vote (53.58%) we get a predicted Clinton vote of 54.8%, with a 95% confidence interval ranging from 50.97% to 58.63%. Anything outside this range would be very surprising.

Reminder: this model does not include state for which pre-election polls were too sparse to create estimates. Also, including Florida in the analysis changes to prediction only slightly (54.6%).

1 comment:

scott said...

obama was one of the leaders of the million man march with farrakhan and sharpton.