Nate Silver @NateSilver538
@adrian_gray @jbarro In principle, it's the same as in a general election, i.e. we look at where a certain pollster's polls compare to the trendline/average in each state for each candidate. e.g. if Warren polls at a 19 in a state where she's at a 17 in the average, that's a Warren + 2 house effect. — PolitiTweet.org
