Smart Politics normally does not blog on the results of a single poll; this site endeavors to provide more than the horserace angle to politics. However, the recent Minnesota Poll released Sunday night does warrant some discussion.
DFL nominee for US Senate Amy Klobuchar now leads GOP nominee Mark Kennedy by 24 points, 56-32, according to the latest poll conducted for the Star Tribune. The poll was conducted September 13-15 with a random sample of 820 likely voters and a margin of error of ±3.4 percent. This marks an uptick in 7 points for Klobuchar from the latest MN Poll conducted in early July when she led 50-31. Independence candidate Robert Fitzgerald received 3% in both polls.
In recent years the MN Poll has been the target of attacks, largely by republican supporters, who have alleged the poll is biased in some way to favor DFL candidates. The evidence for such bias, however, is rather thin. The standard argument presented by critics of the MN Poll is that republican candidates consistently receive a relatively higher percentage of the vote on Election Day than they do in the MN Polls running up to the election, compared to DFL candidates. Citations usually include the 1998 gubernatorial race and the last two presidential elections.
Putting aside the fact that these polls under scrutiny were conducted before Election Day (providing a 'snapshot' of the electorate, it is argued, and not an exact predictor of the electorate's behavior on Election Day), an additional defense of the MN Poll is that the Election Day results for republican (and democratic) candidates do normally fall within the margin of error of the last MN Poll.
Therefore, to claim the MN Poll is (purposefully) depressing republican numbers is to fundamentally misunderstand what the poll numbers represent. Of course, the media is also partially responsible for not helping to educate the public as to the meaning of concepts such as 'margin of error' (with methodological details usually absent in broadcast coverage and buried in the footer of print coverage).
Defense of the MN Poll aside, these new numbers in the US Senate race are quite shocking, and fall outside the range of all other independent surveys conducted in recent weeks (polls that all show Klobuchar leading, but not by this wide of a margin).
The theoretical range of Klobuchar's current lead in the MN Poll—taking in consideration the poll's margin of error—is somewhere between 17 and 31 points. Surveys taken during the two weeks prior to the MN Poll's survey found Klobuchar up by 7 points (Rasmussen), 9 points (Zobgy/WSJ), and 10 points (USA Today / Gallup)—or a range of 3 to 14 points when taking each poll's margin of error into account.
The Star Tribune itself is perhaps a bit surprised at the numbers MN Poll Director Rob Daves reported back to them this weekend before the new survey went public; read the recent blog by the Star Tribune's own Eric Black on this topic, and you can feel the paper already bracing for the backlash.
Smart Politics will certainly not lead or follow any such charge against the Star Tribune nor the esteemed long-running polling institution. But, given the results of other independent polls and past US Senate election results in the Gopher State, it would seem more likely that Klobuchar's actual lead is closer to this side of 15 than that side of 25. And don't be surprised if the race gets much, much closer.