So as of this morning we have seven new polls conducted all or in part after results of the Iowa Caucuses were known. The spin-debate dejour is whether Barack Obama received a "bump," and if so, how much. It is, unfortunately, hard to answer that question given the uncertainty of weekend interviewing and the hard decisions that New Hampshire Democrats are now working to make. Let's look at what we know.
Obama is certainly rising, the only question is by how much. As the table below indicates, all seven polls show some increase in Obama's share of the vote. It ranges between 2 and 10 percentage points, with an average of gain of six points and a median of 5, although the most respected New Hampshire pollster on the list -- CNN/WMUR/University of New Hampshire -- shows a smaller slightly smaller 3-point gain.
With two notable exceptions (ARG and RasmussenReports), the surveys show a very close race. The average of the seven gives Obama a three-point edge, while the median shows Obama up by two. Our regression trends (which should update on our New Hampshire page shortly) show Clinton with a one-point advantage (33% to 32%) on the standard estimate, but a point down (32% to 33%) on the more sensitive estimate. All of these differences fall well within the the margin of real-world and "sampling" error.
However, Obama appears to be gaining. So how big will the bump be? Firm conclusions are premature for two important reasons.
The first involves the issue of weekend interviewing, or more specifically, surveys based on interviews completed entirely on Friday night and Saturday. Most campaign pollsters are reluctant to put too much faith in interviews conducted at those times, when younger and more mobile voters are less likely to be home. In my 20+ years of looking at surveys conducted for campaigns, I can remember only one we did based solely on Friday and Saturday interviewing. In that case even after we weighted by every demographic variable available to make it comparable to others conducted just days before, we produced a weighted sample that appeared much more engaged in politics and better informed about issues and candidates (and thus, more likely to be "certain" about their initial vote preferences).
On the other hand, I cannot claim much experience with weekend interviewing -- my sample size is just one survey. Media pollsters are obviously more willing to conduct such surveys, particularly over the last weekend before an election. So I am willing to suspend disbelief, although I will have a lot more faith in the releases based on interviews conducted through Sunday night.
An aside: When pollsters like me worry about "weekends" we mean Friday night and Saturday, not Sunday. Actually, late Sunday afternoons and evenings are among the best times to catch people at home, especially in the winter. And I see much less to fear from a survey that begins calling on Friday and finishes on Sunday, so long long as all of the "no answer" numbers from Friday and Saturday get dialed again on Sunday night.
The second and more important reason to be cautious about this Sunday morning snapshot is that New Hampshire voters are still in the midst of a difficult decision. The CNN/WMUR/UNH survey tells us that only 52% of Democrats are "definitely decided" about who they will support, while 26% are "leaning toward someone" and 23% are "still trying to decide." Obama has an advantage over Clinton among the definitely decided (41% to 35%; n=183), while Clinton has a slight edge -- for the moment at least -- among those leaning or uncertain (31% to 23%; n=173).
But as you step away from the trial heat results and look at other internal measures, we see why the choice is difficult. Voters like all three of the leading candidates. For example, among the 82 respondents that are "still trying to decide:"
92% rate Obama favorably, only 3% unfavorably
81% rate John Edwards favorably, only 5% unfavorably
75% rate Clinton favorably, only 5% unfavorably
Those same uncertain voters (n=82) also choose:
Obama over Clinton as "most inspiring" (68% to 8%)
Clinton over Obama as the candidate with "the right experience" (53% to 4%)
Obama over Clinton -- though narrowly and with more uncertainty -- as "most likely to bring needed change" (34% to 22%). Obama has a bigger advantage on this measure (40% to 27%) among those who are "leaning" to their choice.
One more thing. I cannot point to an academic study to prove this, but most campaign pollsters will tell you that when a candidate is gaining, vote preference is usually the last thing to change. The movement usually shows up first on internal measures. So on that score, consider that the UNH survey, which shows the smallest "bump" also shows a huge shift on perceptions of electability. Ten days ago, likely Democratic primary voters in New Hampshire considered Clinton the "candidate with the best chance of defeating the Republican" by a a two-to-one margin (45% to 22%). Obama has closed that margin on the most recent survey to a single percentage point (Clinton 36%, Obama 35%).