4 Reasons the Polls Weren't as Wrong as You Think
Donald Trump's presidential victory came as a surprise. The media had built up Clinton's inevitability, and the polls gave her a clear lead. But even before the surprising results came in, pollster Nate Silver noted three major reasons to doubt the polls' predictive certainty.
As voters headed to the polls on Tuesday, FiveThirtyEight gave Clinton a 72 percent chance of winning and estimated that she would win an average of 302 electoral votes.
Nevertheless, Silver emphasized three large caveats: that Clinton's lead was in the margin of error, that the number of undecided and third-party voters was large and likely to skew one way or another, and that Clinton's coalition was not well suited to delivering an Electoral College victory.
These are important caveats, and they show the unavoidable weaknesses of polling. A final weakness had been long spoken of within the Trump camp — what might be called the "Brexit" effect. Trump voters might not identify as such in polls, for important reasons.
These factors combined to destroy the assumptions which pollsters routinely make, and to undercut the predictive power of polling. In other words, pollsters are not to blame that they were wrong, and we should not take the results of this election as proof that in the indelicate words of Sarah Palin, "polls are for strippers and cross-country skiers."
Here are 4 reasons why, with all respect to PJ Media's own Michael van der Gailen, this election did not prove that we shouldn't trust the polls.
1. The margin was closer than you think.
On average, presidential election polls taken the week before the election have been wrong by about 2 percentage points. The error has been even farther off in the most recent presidential elections. In 2000, George W. Bush led Al Gore in the polls by 3 percentage points. Then he lost the popular vote. In 1996, polls underestimated Bill Clinton's re-election by 3.3 percent.
Polls had Ronald Reagan winning in 1980, but they underestimated his margin of victory — by 7.2 percent!
This means that when the polls overestimated Clinton's support by 3 percentage points, they were in keeping with the historic margin of error in presidential elections. According to the RealClearPolitics average, Clinton led Trump by 3.2 percent in the polls, and beat him in the popular vote by 0.2 percent.
This three-point difference is one of the major reasons why, even when sites like FiveThirtyEight were rather confident Clinton would win, they still gave Trump about a 30 percent chance of winning. Don't discount that chance — it's a great deal higher than zero.
Next Page: Undecided voters.