Cell Phones and the 2008 Vote: An Update
Pollsters are continuing to monitor changes in telephone use by the U.S. public, since most surveys are still conducted using only landline telephones. Growing numbers of Americans are reachable only by cell phone, and an even larger number who have both a landline and a cell phone may be "functionally cell-only" because of their phone use habits.
The latest Pew Research Center national survey, conducted June 18-29 with a sample of 2,004 adults including 503 on a cell phone, finds that the overall estimate of voter presidential preference is modestly affected by whether or not the cell phone respondents are included. Obama holds a 48% to 40% lead in the sample that includes cell phones, and a 46% to 41% advantage in the landline sample. Estimates of congressional vote are the same in the landline and combined samples.
Other recent comparisons between landline samples and combined landline and cell samples have found little or no difference in overall results. In a Pew primary election poll in December 2007, Hillary Clinton held a 20-point lead over Obama in the combined sample and a 17-point lead in the landline sample. In a congressional election poll in October 2006 there was no difference in voter preferences between the two samples. Despite the fact that cell-only respondents are often very different from those reached by landline, the relatively small impact from including cell phone samples is a consequence of the statistical weighting applied to surveys as a standard practice among professional pollsters.
Read the complete findings Cell Phones and the 2008 Vote: An Update on the Pew Research Center Web site.