The Growing Gap between Landline and Dual Frame Election Polls

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.

Across three Pew Research polls conducted in fall 2010 -- conducted among 5,216 likely voters, including 1,712 interviewed on cell phones -- the GOP held a lead that was on average 5.1 percentage points larger in the landline sample than in the combined landline and cell phone sample.

In six polls conducted in the fall of 2008, Barack Obama's lead over John McCain was on average 2.4 percentage points smaller in the landline samples than in the combined samples.

Read the complete findings The Growing Gap between Landline and Dual Frame Election Polls on the Pew Research Center's Web site.

National Homeownership Month

Composite image of modern city network communication concept

Learn the Basics of Broadband from Our Limited Series

Sign up for our four-week email course on Broadband Basics

Quick View

How does broadband internet reach our homes, phones, and tablets? What kind of infrastructure connects us all together? What are the major barriers to broadband access for American communities?

Pills illustration
Pills illustration

What Is Antibiotic Resistance—and How Can We Fight It?

Sign up for our four-week email series The Race Against Resistance.

Quick View

Antibiotic-resistant bacteria, also known as “superbugs,” are a major threat to modern medicine. But how does resistance work, and what can we do to slow the spread? Read personal stories, expert accounts, and more for the answers to those questions in our four-week email series: Slowing Superbugs.