The New York Times is backing away — sort of — from its weekend poll that showed a sudden swing to Republican Pete Stauber in Minnesota’s 8th Congressional District.
In September, the Times found DFLer Joe Radinovich was favored slightly over Stauber among those polled. But the weekend poll put Stauber up 15 percent over the challenger for retiring Rep. Rick Nolan’s seat.
In the September poll, those surveyed disapproved of President Trump’s performance by 1 percentage point; now the poll-takers approved of Trump by 18 percent.
It’s probably not that dramatic a shift, the Times’ Nate Cohen writes, but there’s probably more truth to it than the DFLers who are attacking the poll want to admit, he says.
Minnesota is a tough state for pollsters because its voter file, a data set of every registered voter in the state, doesn’t contain information on partisanship, like party registration or whether people voted in Democratic or Republican primaries.
In contrast with most states, we can’t adjust to make sure we have the right number of registered Democrats or Republicans.
Based on all of the other polls we’ve done, we can say with some confidence that the ability to control the number of registered Democrats and Republicans in a poll is a very important factor in results.
Response rates are extremely low nowadays, and our samples, at 500 per poll, are pretty small. Some of our poll results would have been 10 points different without the ability to weight by party registration or primary vote history, and occasionally even more than 10 points different. (Weighting means giving more weight to respondents from an underrepresented group to ensure the sample reflects the demographic profile of likely voters.) In almost all of these cases, it’s Democrats who have been overrepresented, not Republicans.
Based on that, and as we wrote at the time, we decided in September to largely avoid districts without party registration or primary vote history, including some places we’d really like to poll, like Montana or Minnesota’s First and Seventh Districts. For the same reason, we also considered not re-polling Minnesota’s Eighth.
It would be foolish to rule out the possibility that this poll result would have been 10 points different if we could have weighted by party registration, given that we know it has had that kind of effect in other districts. One could find additional evidence for this case by looking at President Trump’s approval rating and the party identification of the poll, two measures that lurched far to the right even though we don’t have much reason to believe that either ought to have moved so far.
If the Times had weighted party affiliation in the same manner it did in September, the Stauber lead would be narrower, but he’d still be up by 4 points, Cohen says.
But Cohen also makes a case for why the shift to the right is real; Republicans are running more ads in the district than DFLers are, the survey is now including the independent candidate in the district, the Kavanaugh Supreme Court fight, and the fact that northern Minnesota is now a socially conservative district.
“I’m just floored to read what Nate Cohn wrote,” Donna Victoria, who polls for the Radinovich campaign, tells the Timberjay. “They sold this poll for four days essentially as entertainment. Now Cohn’s written an article saying it could be off by as much as ten points?”