Forecast update: 25 July 2014

Forecast b 140725 Continue reading Forecast update: 25 July 2014

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Extreme events and probabilistic election forecasting: salutary lessons from football

In his article on last week’s forecast, John Rentoul wrote:

“Probability is hard enough to understand anyway, of course. Look at Nate Silver, the guru of American election predictions. He said Brazil had a 65 per cent chance of winning against Germany in the World Cup semi-final. Well, you could say that their 7-1 defeat fell in the other 35 per cent but – after the event – we can be pretty confident that the 65 per cent figure meant little useful.”

There are various issues here in the context of the overall article. Did the 65% figure mean little useful? How should we judge probabilistic forecasts after the event they were trying to predict? Even if John Rentoul’s interpretation here is right, should the poor performance of a football match prediction undermine the credibility of other forecasting exercises of very different kinds of events for the forecaster, or even for all forecasters? Continue reading Extreme events and probabilistic election forecasting: salutary lessons from football

Leadership effects and electoral cycles

In his article on our 11 July forecast, John Rentoul wrote:

“My view, and this cannot be based on opinion polls, is that when the voters come to choose they will shy away from the prospect of Miliband as prime minister, just as they shied away from Neil Kinnock in 1992.”

This view is not so far from being based on opinion polls as suggested. Continue reading Leadership effects and electoral cycles

Speculation on parliamentary arithmetic

This is the second in a series of posts in response to John Rentoul’s excellent article, much of which discussed the politics of our 11 July central seat forecast (Con 296, Lab 295, LD 31; so either Con+LD or Lab+LD would have a majority).

I have mixed feelings about speculation on the parliamentary arithmetic of any particular forecast. Part of the point of the forecasting method is to estimate uncertainty, which is naturally huge this far away from an election. Continue reading Speculation on parliamentary arithmetic

Fluctuations in polls and the timeliness of the forecast

Belated thanks to John Rentoul for his excellent article on last week’s forecast. This is not to say that I necessarily agree or disagree with his views on the desirability of particular election outcomes, just that I think it is a good discussion of lots of issues in politics and forecasting. Continue reading Fluctuations in polls and the timeliness of the forecast