Earlier today Todd posted on the Rasmussen Poll showing Hillary Clinton holding a double-digit poll over both John Edwards and Barack Obama. Republican pollster Strategic Vision is out today with its own numbers out of Iowa which show a slightly different race -- one in which Clinton leads, but not everwhelmingly so. The latest numbers are as follows (along with the Pollster.com trend estimate, which includes Rasmussen but not Strategic Vision):

Strategic Vision, 600 Democratic LVs, October 12-14, MoE +/- 4%

	Strategic Vision (9/23)	Pollster Average
Clinton	28 (24)	28.7
Obama	23 (21)	23.3
Edwards	20 (22)	21.3
Richardson	9 (13)	10.2
Biden	6 (4)	N/A
Dodd	1 (1)	N/A
Kucinich	1 (1)	N/A
Undecided	12 (14)	N/A

Strategic Vision's numbers run a bit more closely to the Pollster.com average than do those from Rasmussen, and the trend from the GOP polling outfit seems to mirror the trend found by Pollster.com as well. Specifically, as Edwards has steadily lost support since about April and Bill Richardson has lost some support since the summer, both Clinton and Obama have been steadily gaining ground among Iowans.

To take a step back from these specific numbers, I think it's worth asking a fundamental question about polling the Iowa caucuses: How do you come up with a turnout model when you don't know what day the caucuses are going to be held? Specifically, does anyone actually believe that turnout for a Thursday night January 3 caucus, when many voters just won't have the time to take two hours to participate, would be the same as the turnout on a Saturday afternoon January 5 caucus, when significantly fewer voters will be working or have just gotten off of work? Might not the turnout also be different were the Democratic caucuses to be held on Tuesday night January 14, which Ben Smith says is a possibility?

It could be the case that the sentiments of voters 1 through 125,000 are not terribly different from those of voters 125,001 through 150,000 or 175,000 or 200,000. But then again, it also could be the case that those going to caucus for the first time ever or even the first time in many years are a whole lot different from those who are already pretty determined to keep up their streak of making it to the caucuses every four years.

I don't mean to discount the polling conducted on the race. I think it still provides a good snapshot into things and enables us to at least grab on to a tangible metric to gauge how the race is going. At the same time, it's just not clear to me that the numbers we're seeing today mean as much about what's going to happen in January 2009 2008 as a lot of folks would have you believe.