Some telephone surveys skewed by cell phone-only users

According to a study by the Pew Research Center, 12.8 percent of U.S. households cannot be reached by a telephone survey because they have only a cell phone and no landline telephone. If these people were just like those with landlines, this would not create a problem for researchers. But cell phone-only adults are very different.

Cell Phone Only

A growing number of Americans rely solely on a cell phone for their telephone service, and many more are considering giving up their landline phones. This trend presents a challenge to market research and public opinion polling conducted by telephone, which typically relies on a sample of the population of landline subscribers.

The National Health Interview Survey, conducted by the Pew Research Center in conjunction with the Associated Press and AOL, found cell phone-only adults to be younger, more heavily African-American or Hispanic, less likely to be married, and less likely to own a home than adults with landline telephones. These demographic characteristics were correlated with a wide range of social and political behaviors.

In early 2003, just 3.2 percent of households were cell phone-only. In the fall of 2004, the National Election Pool’s exit poll found that 7.1 percent of those who voted on Election Day had only a cell phone. At the annual meeting of the American Association for Public Opinion Research, a government researcher predicted that the size of the cell phone-only group could approach 25 percent by the end of 2008 if the current rate of increase is sustained.

Landline Only

According to data from the National Center for Heath Statistics, 37% of Americans have only a landline. Like the cell phone-only population, Americans who use only a landline only are demographically distinctive. A much higher percentage (41%) are ages 65 and older, compared with the general public (16%). The landline-only group also includes a greater proportion of whites (82%) than the general public (73%).

About a quarter of landline users (23%) say they are very (8%) or somewhat likely (15%) to stop using their landline and switch to using only a cell phone. A much higher percentage of young people (40% of those under age 30 vs. 19% of those 30 and older) say they are likely to abandon their landlines.

The Bottom Line

Political polls can be weighted to offset the effect of the cell phone-only population. However, because of the rising number of Americans who no longer use landline phones, there is growing concern about how long the landline telephone survey will remain a viable data collection tool for traditional market research.