Do states have 'house effects' when it comes to polling?

President Obama greets the crowd in Las Vegas, Nevada, on Sept. 30, 2012.

In late November, the sage of the Sagebrush, Nevada, journalist Jon Ralston, uncovered a fascinating post by UNLV political science professor David Damore. The subject was one that has been often discussed both here and elsewhere: Why are pollsters always getting Nevada wrong?

For those with short memories, in 2008, polls showed Barack Obama with a slight lead in Nevada. When the votes were tallied on Election Day, it wasn't even close'Obama wound up winning the state by a 55-43 margin.

The failure of pollsters to nail the Silver State was even more glaring in 2010, when virtually every pollster in existence had Republican Sharron Angle dispatching Democratic Senate Majority Leader Harry Reid. As it happened, Reid was the victor, and it really wasn't terribly close (50-45).

While the polling this year wasn't quite so far off the fairway (the polls only underestimated Obama's margin of victory in Nevada by roughly three points), once again the Democrat looked better on Election Day in the state than he did in pre-election polling.

Which begs the question that Damore sought to answer: What is it about Nevada?

Some of the expected perils were cited by Damore (a high proportion of Latino voters, as well as a higher-than-normal number of cell phone-only households). But Nevada also had a few other interesting eccentricities that would make it tough to poll, according to Damore:

• The state's largest source of employment, the hospitality industry, necessitates that many Nevadans work and live non-traditional schedules.
• During the past two decades, Nevada has been the fastest growing state in the country and the state has some of the highest rates of annual in and out migration as just 24.3 percent of residents were born in the state; the lowest share in the country.
• Nevada's voter registration is highly variable.  Between March and October statewide voter registration increased by 21 percent and in Clark County, home to nearly three quarters of the state's population, registration increased by 26 percent.

Even though the effect wasn't quite as magnified in 2012, it was still present. In the nearly two dozen polls conducted after Oct. 1, President Obama led by an average of 3.6 percentage points. At last check, the margin was 6.7 percent. A similar overstatement of Republican performance was present in the state's Senate race: The polls had Republican incumbent Dean Heller up quite a bit more than the final margin, which landed at just a tick over one percent.

However, Nevada is not the only state where this phenomenon was present. And, the multiple examples of states that seem to defy pre-election polling raises the question as to whether a "house effect" exists in states.

(Continue reading below the fold.)