Senate poll: Who to believe?

Last evening, A Survey USA poll done for KSTP showed Norm Coleman well out in front of Al Franken in the race for Minnesota’s U.S. Senate seat. On Saturday morning, a Minnesota Poll for the Star Tribune showed Al Franken well out in front of Norm Coleman for Minnesota’s U.S. Senate seat.

I know what you’re thinking: Something’s messed up here.

Over at MinnPost, politicos David Brauer and Eric Black parsed the two polls and found it appears to hinge on the Star Tribune’s practice of weighting the pool of respondents in favor of Democrats, figuring that more Democrats will vote in November than Republicans.

The Star Tribune poll involved more respondents contacted by a human on the telephone. Survey USA was a robopoll — an automated voice guides the person taking the poll.

Whose poll is more accurate? That’s the great thing about being a pollster. By the time someone checks your work, you’ve cashed the check and, besides, polling is just a snapshot in time. It’s not a projection.

But that won’t stop me from looking back and checking anyway.

In the last race for a U.S. Senate seat, the final Survey USA poll ( a day before Election Day) showed Amy Klobuchar ahead of Mark Kennedy 56-to-40 percent. She won 58-to-38 percent.

Conclusion? It was a heck of an accurate poll. The same poll, by the way, had Tim Pawlenty and Mike Hatch tied at 45%. And, indeed, when all was said and done, Mike Hatch lost by 1 percent of the votes cast.

A Star Tribune poll at the same time, had Klobuchar up 21 percent. Close, but not as close as Survey USA. (Updated: This is incorrect as David pointed out. Strib closer than Survey USA)

About 6 weeks before the election, Survey USA had Klobuchar up by 8 points, with Pawlenty and Hatch separated by 1 percent in favor of Pawlenty. Star Tribune had Klobuchar up 24 points.

So this isn’t the first time these two polls have been very different, but the current differences are unusually stark. The Democrats will say the Star Tribune is the accurate poll. Republicans, who’ve made a cottage industry out of assailing the Minnesota Poll in the past, will swear by the Survey USA poll.

As the saying goes, past performance is no indicator of future results. But where polling is concerned, it’s at least as good as any other guesswork that’s out there.

  • Bob – thanks for the llinkage. Two observations:

    1. The Strib might not be “weighting” their poll toward Democrats – in fact, it could be they decided not to weight at all (some polls do), meaning they didn’t try to hit some pre-arranged, historically defensible party ID targets.

    Some polls drop such weighting as we get down the stretch – don’t know if the Strib is one, but just noting it here because of your verb choice.

    2. Regarding the Minnesota Poll’s history, it’s a great point by you – with one caveat. The Strib used its own internal pollster in 2006 (Rob Daves) and now – as a result of budget cutting – uses Princeton Research Associates.

    In other words, PRA doesn’t really have a track record yet – though your point is ultra-salient in noting SUSA’s historical record and the regularity with which the GOP attacks the Minnesota Poll.

  • One other thing I just noticed (maybe I’m gleaning wrong):

    Klobuchar beat Kennedy by 20, right? If SUSA’s last poll had her up by 16, and the Strib had her up by 21, isn’t the STRIB “closer” rather than SUSA, as you write?

    Both polls did well, but it looks like the Strib’s did really well.

  • Joshua

    Hey Bob, I know this probably isn’t your gig, but who approved the mpr main page photo of the three candidates. Barkley and Coleman looking disheveled, caught off guard, and under exposed, meanwhile Franken is centered and brightly lit with a big red tie. It looks a bit biased. Probably not the image MPR wishes to purvey.

    Hope the debate is cruising along nicely.

  • Bob Collins

    Joshua: You’re right. I have nothing to do with it. It’s one of the joys of leaving the managing editor job behind a year ago.

  • Bob/David,

    Historically, 2006 was an outlier; the Strib/Minnesota poll has always overrepresented and over-everything’ed Democrats – and for once, in ’06, circumstances warranted it.

    In ’04, they showed Kerry beating Bush by a vastly bigger margin than transpired.

    In ’02, they showed Mondale handing Coleman his head, and within the month before the gubernatorial election showed Moe pulling ahead of a three-way tie with Tim Penny. It certainly didn’t turn out that way.

    Scott Johnson at Powerline went into a long history of similar heavy advantages to DFLers; Humphrey/Ventura/Coleman, Grams/Wynia and on and on and on.

    The Minnesota Poll is redeemable only as comedy fodder.