As you can imagine, it’s being held up by Drudge and most McCain supporters as the latest “evidence” that the race is tightening, but there’s reason to take the poll with a grain of salt, or at least the supposed big change from last weeks’ poll.
Basically, they cooked the books.
Here’s the sample breakdown, by party, from last week’s Fox poll:
Democrats 401, ±5 percentage points; Republicans 345, ±5; independents 148, ±8 Obama supporters 462, ±5; McCain supporters 370, ±5
And here it is from this week:
Democrat LV 379, ±5; Republican LV 364, ±5; independent LV 146, ±8, Obama supporters LV 439, ±5; McCain supporters LV 405, ±5
There’s a difference, not a big one, but as Marc Ambinder notes, in polling small changes can have a big impact:
I’m no expert on this question, so I asked Mark Blumenthal of Pollster.com what he thought.
He tells me: “If they have been weighting by party, and they suddenly changed their weighting, I’d say it’s a pretty questionable practice. The last four Fox surveys all varied slightly in terms of party ID, so I’m not sure that’s what they’ve done. That said, if the other surveys this week show no similar “shift” in party, then it’s probably reasonable to discount this result.”
Odds are it’s an outlier.