
Nate Cohn @Nate_Cohn
Let's take an extreme example to illustrate: suppose a 50-50 race with *100%* turnout, and suppose 100% of Party A votes early, while no one in party B votes early. That poll will be biased toward party A, unless it assigned 100% turnout to all of party B (which wouldn't happen) — PolitiTweet.org