Support for Sweden Democrats Is Anyone's Guess as Polls Differ

(Bloomberg) -- Sweden’s political world could either experience a medium tremor or a major quake next month depending on which poll you trust.

Different pollsters are showing wildly different results for the Sweden Democrats (SD), but they are all in agreement that the nationalist, anti-immigration upstart will make major gains in the Sept. 9 election.

According to YouGov, the party is set to overtake the ruling Social Democrats as the biggest party, with backing of 24.2 percent in its most recent poll. Sentio Research estimates its support will rise to 21.8 percent. At other pollsters, it averages 19.1 percent.

Support for Sweden Democrats Is Anyone's Guess as Polls Differ

The spread between YouGov’s poll and Sifo’s is equal to roughly 20 seats in Sweden’s 349-member parliament.

The bigger SD gets, the more clout the party will have. Neither of the traditional political blocs in Swedish politics will likely emerge with a majority with the support for SD set to surge from the 12.9 percent it secured in the 2014 election. As kingmakers, the party may therefore be able to block budgets and reforms as it sees fit.

Sentio was the most accurate pollster in 2014 in predicting the support for SD, seeing it at 12.7 percent. YouGov was also pretty close at 11.1 percent. Many other pollsters underestimated support, predicting it would stay below 10 percent.

Support for Sweden Democrats Is Anyone's Guess as Polls Differ

It’s not just in Sweden that pollsters have failed to accurately assess voter sentiment. They to some degree underestimated support for Donald Trump in the U.S. presidential election and for Brexit in the U.K.

To a larger extent that the traditional pollsters, Sentio and YouGov use web-based panels, which anyone can register for. As few Swedes wanted to publicly identify as Sweden Democrats back in 2014, that method has been credited with giving them a more accurate reading of voter sentiment.

"There is a great discrepancy between the institutes measuring over the web and those who measure of the phone,” said Arve Ostgaard, a senior adviser and founder at Sentio. “But the Sweden Democrats are getting more and more accepted and that’s why they are also gaining among those measuring over the phone."

The party has become more accepted as it has become bigger and has also booted out more extreme and even outright racist elements. Many other pollsters have adjusted their methods after 2014, changing their weightings to account for those who don’t want to say they plan to vote for the Sweden Democrats or using a mix of phone and web polls.

Lars Gylling, Nordic communication manager at YouGov, says that while there are big differences between the polling firms and a general tendency to underestimate the party, things have likely changed since the 2014 election.

"What we see is that both Sentio and YouGov see the Sweden Democrats higher than the other polling firms, but we also know that the other polling firms have changed their methods," Gylling said. Another difference is also that the party has become more accepted, he said. "When a party is growing, and you have friends saying they will vote for them, it’s easier to say that you will vote for them too."

Torbjorn Sjostrom, the chief executive officer of pollster Novus, said there is no evidence that web-based interviews are more accurate than phone-based ones. According to him, they’re only slightly more scientific than tea-leaf reading.

Sentio may have been the most accurate on the Sweden Democrats in 2014, but it wasn’t as accurate on most of the other parties.

"In order to be a part of these self-recruited panels, all you need is an email address, so you easily get an over-representation of activists who are out to influence the election," Sjostrom said. Novus has now adjusted its methods to avoid underestimating SD, he said.

Then there are the betting companies.

If they are to be believed, SD will become the biggest party. At Betsson, a bet on that pays just 1.7 times the money, the lowest among all parties. A bet on the Social Democrats will return 1.85 times, while a bet on the Moderates will yield 12 times the money.

Support for Sweden Democrats Is Anyone's Guess as Polls Differ

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