It Wasn't the Polls That Missed, It Was the Pundits, por Sean Trende (Real Clear Politics):
There is a fast-building meme that Donald Trump’s surprising win on Tuesday reflected a failure of the polls. This is wrong. The story of 2016 is not one of poll failure. It is a story of interpretive failure and a media environment that made it almost taboo to even suggest that Donald Trump had a real chance to win the election.
At RealClearPolitics, we know that the RCP Poll Average is a powerful tool for gauging election trends and projecting outcomes. But we also recognize that it is not a perfect tool, and that even when aggregating multiple polls, the margin of error within each survey allows for a range of possibilities to exist.(...)
That is why, early on, we took what some thought was an unusually broad view of what constituted a tossup state, before returning to our traditional definition of a tossup as a state whose separation is less than five points in the RCP Poll Average. So when a state like Pennsylvania, where Clinton led by 1.9 percentage points in the final RCP Poll Average, goes the other way, we aren’t shocked. (...)
Though the conventional wisdom had written off Trump’s chances by Election Day, there was evidence showing it was still a very competitive race. The final RCP No Tossup Map, based off the final RCP Poll Averages in the battleground states, had Clinton leading by the slimmest of margins in the Electoral College 272-266. (...)
At 266 electoral votes, Donald Trump stood just one state short of winning the presidency. And with the final RCP Poll Averages in a handful of battleground states showing Trump trailing by just 0.6 percent in New Hampshire, 1.9 percent in Pennsylvania, 2.9 percent in Colorado, and 3.4 percent in Michigan, it was pretty clear that Donald Trump had a very real path to the White House.