Effect of Cell Phone Samp les on Presidential Horse Race Estimates
To address this challenge, the Pew Research Center for the People & The Press included cell phone samples in all of its fall election polls, and many other major pollsters took similar steps. All of the Pew Research Center’s election survey reports were based on data from both landline and cell phone interviews, using a methodology described below. The addition of cell phone interviewing had at most a modest effect on estimates of candidate support in most of those individual surveys. When looked at in the aggregate, however, clear patterns emerge.
Effect of Cell Phone Samp les on Presidential Horse Race Estimates  | 60  | 50  | 40  | 30  | Obama's advantage in landline and cell sample  | +8  | +3  | +7  | +10  | +14  | +11  | 20  | Obama's advantage in landline sample alone  | 10  | +6  | +10  | 18  | +11  | +6  | Q  | Jun 18-29 Aug 1-10 Sep 9-14 Sep 27-29 Oct 9-12 Oct 16-19 Oct 23-26 Oct 29-  | Nov  | Landline and cell sample  | Obama  | Itccain  | Landline sample alone  | Obama  | Accain  | Figures based on registered voters and include those who "lean" toward a candidate 