Fundamentals, Polls, and the Primary - The New York Times:
"The huge polling miss in Michigan was a cautionary tale: for all its excellence, FiveThirtyEight is only as good as the polls, which at least this time were way, way off. It’s too soon to dismiss them, but not too soon to explore other approaches, which is what Alan Abramowitz has just done. Using data for the Dem contests so far, he estimates a simple relationship based on just two factors — nonwhite share of the population, and north versus south — that accounts for the results quite well — and Michigan is not an outlier."
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