Nate Cohn @Nate_Cohn
4) A good Iowa caucus poll, I should note, is pretty costly. Iowa Dem caucus goers are like 10% of RVs in the state, so you need a big smaple. Those CNN/DMR/Selzer polls sometimes breach N=3000; ours was N=1500 with a 50% D oversample, and that's only bc we're off the voter file — PolitiTweet.org