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Cell Phone Update

Topics: Cell Phones

Yesterday, the National Center for Health Statistics (NCHS) released its latest estimates of the number of Americans living in households without landline telephones, as well as a statistic closely watched by pollsters: During the first six months of 2006, "approximately 10.5 percent of households do not have a traditional landline telephone, but do have at least one wireless telephone."

Pollsters have been watching the growth in "cell phone only" households because cell phones are largely out of reach of the traditional random digit dial sampling methods used in most conventional telephone surveys. As such, the continuing upward tend in such households illustrated by the NCHS surveys (which involve massive monthly in-person samples of Americans), should be of great interest to anyone who follows public opinion polling.

1-18%20NCHS%20fig1small.png

Although I have written about these issues previously (here, here, here and here), the best analysis of how this trend has affected the accuracy of public polling has been done by the Pew Research Center. Last year, in partnership with the Associated Press and America Online, they conducted parallel surveys: One using conventional telephone sampling and another that interviewed a random sample of 750 mobile phone users over their mobile phones. The study produced a report by the Pew Research Center (available in either HTML or PDF format) reached the following conclusions:

[Cell only Americans] are younger, less affluent, less likely to be married or to own their home, and more liberal on many political questions.

Yet despite these differences, the absence of this group from traditional telephone surveys has only a minimal impact on the results. Specifically, the study shows that including cell-only respondents with those interviewed from a standard landline sample, and weighting the resulting combined sample to the full U.S. public demographically, changes the overall results of the poll by no more than one percentage point on any of nine key political questions included in the study.

Of course, given the trend reported by NCHS, the cell-phone only adult population appears to be a moving target. It has more than doubled in the last two years, and the trend shows no signs of slowing. How big a problem will cell-phone only households be in 2008? Will their absence from traditional phone surveys begin to impact results? Will pollsters begin to routinely incorporate more expensive cell phone samples into their surveys? Time will tell.

 

Comments
Jerome:

Am I the only one who wonders whether a decline in the accuracy (and thus, the utility) of polls might not be a good thing?

Poll-driven elections have the effect of driving out less popular candidates far earlier than they might quit electoral races, were they focused more intently on their own message, instead of on people's reactions to it, as shown by the latest polls.

Polls contribute to the homogenization of political rhetoric. Maybe if we didn't know that a candidate was attracting (so far) only 3% of the vote, we might take the time to listen to what he/she is saying. And maybe what the candidate was saying might vary, a tiny bit more, from what all the other candidates were saying.

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BobH:

"younger, less affluent, less likely to be married or to own their home"

Isn't that a pretty good description of a non-voter?

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DWPittelli:

Jerome,

It would be good if the press paid less attention to poll-based "horse-race" stories, in favor of issues stories, but it's unclear that less accurate polls but will force such a change. Did anyone stop paying attention to polls after any of the past polling debacles?

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caplight:

None of my children have landline phones. they make good money, own homes and along with their spouses see traditional phone service as something like their father's Oldsmobile. Many of their friends are same. The profile sounds like it was written by the PR department of a phone company.

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