The latest political polling numbers suggest that poll results sway in favor of one candidate or another depending on whether a pollster calls likely voters on cell phones, Nate Silver pointed out on FiveThirtyEight.com on Sunday.
Silver's analysis shows that out of 14 polling organizations, the five that call likely voters' cell phones (shown in gold in the accompanying chart) put Democrat Barack Obama ahead of Republican John McCain by an average of 9.4 points. By contrast, the eight pollsters that do not call cell phones have Obama ahead by 5.1 points.
The data mirrors studies that suggest likely voters who only use cell phones are more likely to vote for Obama. The Pew Research Center last month released a study showing that cell phone users favor Obama more than landline users by at least 10 points.
Cell phone users have presented a challenge to pollsters because they may no longer live in the state to which their phone number corresponds, and the cost of using cell phone minutes could affect their participation in polls.