The Philadelphia Inquirer reported that the growing use of cellphone- only households has made conducting political surveys more difficult. "Nationwide, the proportion of cellphone-only households has doubled in less than four years, from 17.5 percent in the first half of 2008 to 34 percent at the end of 2011, according to the most recent government survey. Such people are harder to reach for various reasons. Even in those households with land lines, residents are increasingly less likely to pick up the phone. Caller ID is widespread for those who want to screen out unwanted calls. Amid rising concerns about identity theft, some people are loath to divulge the kinds of personal information polls seek."
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