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 pored over by analysts and candidates alike but the real indicative value can sometimes, with the benefit of hindsight, be limited.
The infographic below takes a look at the final poll conducted by Gallup before each Presidential election since 1976. While the majority of polls predicted the overall winner correctly, the first year under consideration here was an exception. Carter vs. Ford was predicted to be a 1 point win for the Republican candidate, with Carter actually winning by 2 points. Most recently, the final poll in the 2012 election had Obama trailing Romney by 1 point, only for the incumbent President to dominate the ballot boxes by almost four points come election day. While many are expecting a Democrat landslide in 2016, with Clinton well in front in the polls, it is understandable that Hillary's campaign team are still remaining cautious on their chances.
The Statistics Portal
Statistics and Studies from more than 18,000 Sources
ProductsAdvertising on Statista (PDF)