The GOP gained control of the Senate Tuesday night, taking hold of the legislative agenda in that chamber. Here are three of the policies Republicans are likely to tackle as they take the reins in January 2015. (Julie Percha/The Washington Post)

For Tuesday night to have been a shocker, the polls needed to have been generally wrong in one direction or the other. Democrats were fervently hoping that polling was undercounting their turnout efforts and that they'd be able to overwhelm their opponents with a surge in votes. Instead, the surprise was how handily the Republicans won -- in part because they almost uniformly did better than polling averages, even when they lost.

Real Clear Politics compiles a running polling average of how surveys unfold over the course of a campaign. The average includes nearly any poll, including those of lower quality, but is generally seen as one of the more useful guides to the state of a race. And in nearly every contested Senate race last night, the GOP beat the RCP average.

The graph below compares actual GOP margin (vertical axis) with the RCP average (horizontal). Dots are colored according to the party that won; dots that are in the red-shaded area were Republicans who outperformed polling; those in blue, Democrats who did. Overall, Republicans who beat the average did so by six points; Democrats by just under one point. Across all contests, there was a 4.6 percentage point overperformance by Republicans.


Democrats did better than expected in Michigan, Minnesota and Montana -- but almost certainly all within any margin of error. Sen. Jeanne Shaheen in New Hampshire did best of all of the Democrats.

Republicans in every other race outperformed. Even in New Jersey, where Cory Booker (D) walked to reelection, he didn't do as well as polling predicted. In fact, as the dotted red line shows, Republicans did better against the polling average the better they did in their races.

Politicians often claim the polls are wrong when they're on the brink of defeat. In this case, the polls largely predicted the correct winners, but -- with select exceptions such as the Des Moines Register poll last weekend that showed Joni Ernst (R) ahead by as wide a margin as occurred -- the scale of the victories was way off.

Which is the kind of wrong that victors don't mind seeing.

The GOP gained control of the Senate Tuesday night, taking hold of the legislative agenda in that chamber. Here are three of the policies Republicans are likely to tackle as they take the reins in January 2015. (Julie Percha/The Washington Post)