How Accurate are Election Polls?
In the run up to any election, a lot is made of the numerous polls conducted to gauge the current leanings of the electorate. The results of these surveys are poured over by analysts and candidates alike but the real indicative value can sometimes, with the benefit of hindsight, be limited.
Final polls of US Presidential elections from 1976 to 2012
Politics: "How Accurate are Election Polls?"