I was fair to Michelangelo in my Sistine Chapel post, but misrepresented the estimable Sam Wang.
Sam Wang gives Hillary Clinton a poll-based 70% probability of becoming US President, if the election were held tomorrow ..
That was wrong and I apologise. Wang’s poll-based estimate if the election were held tomorrow is 99%. The 70% is a forward-looking estimate for November, based on the polls to date plus one other piece of information: the historical variance between polling in May and results in November over the last 60 years.
This is informative, and Wang’s austere poll-based purism is a useful corrective to horse-race and economic-fundamentalist narratives. But it’s far from compelling. Wang himself writes:
But considering the upheaval in the Republican Party, a little voice tells me to open my mind to a wider range of possibilities … including a Trump win.
There is no deep reason why we should not peer behind the curtain of historical variation and use the non-polling information we have to improve on what it suggests. We skirt the impenetrable mato of statistical philosophy Brad deLong ventures into here; I hope we see him again. As normal gamblers, let’s take as the question: what reasonably foreseeable factors are capable of changing voters’ preferences for Trump or Clinton between now and the election? I score the downside risk factors unscientifically out of 100, as a prop. Continue Reading…