Pew Research on "The Growing Gap between Landline and Dual Frame Election Polls"

Link to November 22, 2010, report.

Excerpt: The number of Americans who rely solely or mostly on a cell phone has been growing for several years, posing an increasing likelihood that public opinion polls conducted only by landline telephone will be biased. A new analysis of Pew Research Center pre-election surveys conducted this year finds that support for Republican candidates was significantly higher in samples based only on landlines than in dual frame samples that combined landline and cell phone interviews. The difference in the margin among likely voters this year is about twice as large as in 2008.

Related articles:
Taking polls with a grain (or more) of salt. (10/13/2010)
Will most pollsters continue to ignore the elephant in the room?  (5/24/2010)
"Please stay on the line for an important call".  (3/9/2009)
Survey says...omission of cell phone users does make a difference in polling.  (9/24/2008)