and more from the economist: they reckon Hillary has a 96% chance of winning, based on accuracy of past polling and time to election day.
Posted by
mafic
Oct 24 '16, 21:30
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"Methodological appendix: To derive the probability of a victory for Hillary Clinton, we first calculated the historical error rate for polls using a data set of presidential-election polling going back to 1952 compiled by Robert Erikson and Christopher Wlezien, two political scientists. For each day in the sample, we computed the average error from the final tallies, and how much those errors varied from one election to another. We used this mean and standard deviation to fit a t-distribution with 15 degrees of freedom (since our data set consists of 16 elections), yielding a probability for every possible magnitude and direction of error. Based on this distribution and the current polling average as reported by RealClearPolitics, presidential polls two weeks before the vote should understate the trailing candidate’s support by a margin greater than the favourite’s lead just 4% of the time. All analysis was conducted on two-party vote share."
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