With the Iowa caucuses a week away, the American Research Group poll finds a shift toward Hillary Clinton. But is it a bellwhether or an outlier:

Clinton and Obama were neck-and-neck in last week’s American Research Group poll. But in the new survey, conducted December 20-23, she leads the Illinois senator by 15 percentage points, 34 to 19 percent.

Obama is now in a statistical tie for second place with former North Carolina senator John Edwards, who has 20 percent of the vote.