President-elect Donald Trump is again criticizing the polls. In addition to ridiculing 2016 election polls for underestimating his strength, he’s now challenging the accuracy of new national surveys that show his pre-inaugural ratings to be much lower than those of his recent predecessors.
Now that all the votes from the election are in, let’s take a final look at how the polls did in last year’s election. It may surprise you.
Of the 13 final national polls conducted the week before the election that tested the four-way presidential contest, only one had Trump ahead and 12 put Democratic nominee Hillary Clinton on top.
That would seem to be a veritable disaster for the polling industry, right?
National polls only measure the popular vote. Clinton did, in fact, win the national popular vote by 2.1 points. The average of the 13 final national polls had Clinton ahead by 3.1 points, which was only a point off the actual result.
Ironically, all 12 polls that had Clinton ahead turned out to be closer to the final outcome than the poll that had Trump ahead. While that may seem crazy — since Trump, not Clinton, is headed to the White House — it’s true. The poll that put Trump ahead (by 2 points) was off by 4.1 points, while polls that gave Clinton the lead were off anywhere from only one-tenth of a point to less than 4 points.
National polling did much better in 2016 than in 2012, when the average of the final polls in the contest between President Obama and GOP nominee Mitt Romney was off by more than 3 points. Polls showed Obama winning the popular vote by only seven-tenths of a point, and on Election Day he captured a wider 3.9-point vote margin.
Of course, the national popular vote is irrelevant in terms of who wins presidential elections. Only the Electoral College matters. But when a candidate wins one and loses the other, as happened this time, it clouds perceptions of margin size and polling accuracy.
What gave Trump his electoral victory was not his national voter strength — which he lost by nearly 3 million votes — but his strength in eight swing states, which he won by a little over 1 million votes.
Swing state presidential polls: In Florida, the largest of the swing states, the average of the final three polls had Trump ahead by three-tenths of a point. He won the state by 1.2 points. Ohio’s last poll gave Trump a 7-point lead, and he carried it by 8.1 points. The average of the three final polls in Pennsylvania had Clinton leading by a single point and the last poll taken had Trump ahead by a point. He won the state by seven-tenths of a point.
In Michigan, the two final polls had Clinton ahead by an average of only 1.5 points. The later one gave Trump a 2-point lead. He won by two-tenths of a point. The average of the final four polls in North Carolina had Trump ahead by five-tenths of a point, although he won by a more robust 3.7 points.
The final two polls in Wisconsin had Clinton ahead by an average of 7 points, and Trump won the state by eight-tenths of a point. Both polls, however, were completed about a week before the election.
Polls are pictures in time, not crystal balls. They look backward, not forward. They can’t predict what occurs after they’re conducted. When polling shuts down too early, which happened in Wisconsin and other places, it misses the final breaks — and in this topsy-turvy election, it was last-minute movement in a few states that gave Trump his sensational victory.
Exit polling found that late-deciders in Florida, Michigan, Pennsylvania and Wisconsin broke for Trump by double-digit margins as high as 29 points.
With some exceptions, the final polls in key Senate races were fairly close to the actual results. They correctly showed Republicans leading in Florida, Indiana, North Carolina and Ohio, and Democrats leading in Nevada and Colorado. They also showed Democratic challengers easily winning Illinois and barely winning New Hampshire — right on both counts.
In Pennsylvania, five of the last seven polls had the Democratic challenger winning, although the final two polls gave the Republican incumbent an average lead of five-tenths of a point in a race he won by 1.6 points. In Missouri, the last two polls gave the Republican incumbent an average lead of 1.5 points, a race he won by nearly three points.
In Wisconsin, the final polls put the Democratic challenger narrowly ahead, but found that the GOP incumbent was strengthening his position. Ultimately, the incumbent won by more than 3 points. But, just as in the presidential race, the Wisconsin polling was more than a week old.
The bottom line: Whether last year’s polls were accurate or not, nothing excuses bad polling — especially when it’s caused by corner-cutting, biased sampling or faulty methods.
Even though plenty of polls accurately measured races for the presidency, Senate and House, it’s equally true that many were flat-out wrong. To make matters worse, bad polls are often outliers and hit like bombshells, accurate or not. The media uses them to heighten the drama. Partisans use them to prop up their optimism.
Another problem this year was the slew of statistical “models” that incorrectly predicted the election. These calculations are really just educated guesses based on factors that can be influenced by the personal biases of the modeler. They should never be confused with polling.
Polls are imprecise tools with margins of error. But in this tumultuous election — from early primaries in February to the final vote in November — polls came closer to measuring reality than did the pundits and partisans who only saw in the numbers what they wanted to see.
Ron Faucheux, Ph.D., is a political analyst, author and pollster. He publishes LunchtimePolitics.com, a daily newsletter on polls. He also runs Clarus Research Group, a nonpartisan survey research firm.
The views expressed by contributors are their own and not the views of The Hill.