Why Polls Tend to Undercount Democrats [View all]

[IDemo]

Polls show that the Republicans have an advantage in the fight for control of the Senate. They lead in enough states to win control, and they have additional opportunities in North Carolina and New Hampshire to make up for potential upsets. As Election Day nears, Democratic hopes increasingly hinge on the possibility that the polls will simply prove wrong.

But that possibility is not far-fetched. The polls have generally underestimated Democrats in recent years, and there are reasons to think it could happen again.

In 2010, the polls underestimated the Democrats in every competitive Senate race by an average of 3.1 percentage points, based on data from The Huffington Post’s Pollster model. In 2012, pre-election polls underestimated President Obama in nine of the 10 battleground states by an average of 2 percentage points.

<>

But the reasons to think that today’s polls underestimate Democrats are not based on just the last few years of results. They are also based on a fairly diverse set of methodological arguments, supported by extensive research, suggesting that many of today’s polls struggle to reach Democratic-leaning groups.

http://www.nytimes.com/2014/10/30/upshot/why-polls-tend-to-undercount-democrats.html?_r=0&abt=0002&abg=0