Cell-Phone-Only Crowd May Alter Polling

WASHINGTON -- Justin Globus is part of a fast-growing group _ approaching one in 10 Americans _ who have given up traditional telephones and depend only on their cell phones. That trend is making pollsters uneasy.

For Globus, a 25-year-old salesman from New York, "It was a fiscal decision _ a matter of chopping down to one bill."

But the rapid growth of the cell-only crowd isn't so simple for pollsters. Their survey research depends on contacting random samples of households with landline phones. They worry that if the trend continues they could miss a significant number of people and that could undermine their ability to accurately measure public opinion. There could be implications for politics, government policy, academia, business and journalism.

So far, the differences aren't so great and the cell-only group isn't large enough to affect survey accuracy, according to an AP-AOL-Pew study, one of the most extensive news surveys of cell phone users yet.

Currently, 7.8 percent of adults live in households that have only a cell phone, according to research released Friday by the Centers for Disease Control and Prevention's National Center for Health Statistics. And that group is growing at about 1 percentage point every six months.

Those who only have cell phones are significantly different in many ways _ typically younger, less affluent, more likely to be single, and more liberal on many political issues _ from those who can be reached by landline, an AP-AOL-Pew survey finds.

For example, 51 percent of the cell-phone-only group believes gay marriage should be allowed, while 37 percent of a standard polling sample felt that way. And 53 percent of the cell phone only sample said they would vote for the Democratic Party's candidate, while 47 percent of a standard sample said they would vote Democratic, the poll found. Those differences virtually disappeared once the cell-phone-only sample was blended into the total.

About a fourth of the people who use landlines say they are at least somewhat likely to give up their landline and switch to cell phone only, the poll found.

"If it wasn't for our computer, I would have done it already," said 39-year-old Kathy Sharkey of Troy, Texas, married and the mother of three. "I rarely use my home phone. Since I use my cell phone anyway, why pay the extra money?"

Landline surveys may minimize the effect of missing cell-only people like Globus through industry-standard statistical adjustments. Results from a random sample typically are weighted to known demographic parameters of the population, like age, race and sex data collected by the Census Bureau. Since younger people are harder to reach in landline phone surveys, responses from that age group tend to get weighted up.

Blending the opinions of cell-only respondents into a poll of all adults changed the findings on various political questions in the AP-AOL-Pew survey by 1 percentage point at the most.

"Today we're doing pretty well in dealing with the cell phone issue," said Scott Keeter of the Pew Research Center for the People & the Press. "The problem is that the number is growing and at a pretty substantial clip."

The AP-AOL-Pew poll of 1,503 adults included 1,286 cell phone users and was conducted March 8-28. Half the interviews, 752, were conducted by landlines and 751 by dialing cell phones _ including 200 adults who had only cell phones.

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AP Polling Director Mike Mokrzycki and AP Manager of News Surveys Trevor Tompson contributed to this story.

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Pew Research Center: http://www.people-press.org