Have Polls Always Underestimated The GOP Vote?

Knowing that exit polling has historically overestimated the Democratic vote and knowing how much the final regular polling in the 1980 race understated Ronald Reagan’s support compared to Jimmy Carter, it is worth looking at what the final poll results said in other presidential election years.

The facts show a similar trend in a pro-Democratic direction almost uniformly. Historically speaking, pollsters have underestimated how many people would vote for the Republican presidential candidate:

Writing at National Review, reporter Jim Geraghty quotes an anonymous pollster who provides a helpful review of past polling data:

In 1992, Gallup’s final poll had Clinton winning by 12 percentage points, he won by 5.6 percentage points. In late October 1992, Pew had Clinton up 10.

In 1996, some reputable pollsters had Clinton winning by 18 percentage points late, and Pew had Clinton up by 19 in November; on Election Day, he won by 8.5 percentage points… In 2004, pollsters were spread out, but most underestimated Bush’s margin. (2000 may have been a unique set of circumstances with the last-minute DUI revelation dropping Bush’s performance lower than his standing in the final polls; alternatively, some may argue that the Osama bin Laden tape the Friday before the election in 2004 altered the dynamic in those final days.) In 2008, Marist had Obama up 9, as did  CBS/New York Times and Washington Post/ABC News, while Reuters and Gallup both had Obama up 11.

Now, if this was just random chance of mistakes, you would see pollsters being wrong in both directions and by about the same margin in each direction at the same rate – sometimes overestimating how well the Democrats do some years, sometimes overestimating how well the Republicans do. But the problem seems pretty systemic – sometimes underestimating the GOP by a little, sometimes by a lot.

In 2004, the final telephone surveys mostly favored George W. Bush against John Kerry but the exit polls clearly did not. As usual, they overstated the Democrat vote (see our earlier report on reasons for this) which led many Democrats to expect that Kerry would win the popular vote and the presidency. When that did not happen, it triggered a widespread belief among hardcore Democrats that Republicans had somehow managed to “steal” the election in several different states, particularly in Ohio.

Via: Newsbusters

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