Wall Street Journal: “Founders of political wagering site Intrade are back with a new forum for electoral prognosticating, minus one big thing: the wagering.”

“Pivit, a web and mobile application, is launching prediction markets this week for the midterm U.S. elections… Pivit’s contracts are based in percentages, not dollars. Participating doesn’t require any money or pay out any rewards. Instead, the new market aims to attract people with rankings of the best predictors.”

Jonathan Bernstein lists five states “most at risk for polling mishaps” in their Senate elections, ranked from most to least likely: Georgia, Alaska, Kansas, Colorado and South Dakota.

“This doesn’t mean any of them will hold surprises once the votes are counted. It just means that right now there are reasons to look at the polls with some skepticism.”

Harry Enten: “Two weeks and two days before Election Day, and we received just two polls over the weekend. The polls, both taken in Colorado by left-leaning groups, had little impact on the FiveThirtyEight Senate forecast — Republicans have a 62 percent chance of taking the Senate. Indeed, we were more interested in the small number of polls than what those two surveys said.”

“The FiveThirtyEight model relies mostly on polls, and without polls, the forecast’s accuracy could suffer. So we looked into it. Fortunately, this weekend was an aberration. We’re getting fewer polls than we did in 2010, but we’re not getting way fewer polls.”

Sam Wang: “Yesterday, Nate Silver and I both examined Senate polling errors. He saw no overall bias; I pointed out that recent bias has been unusually large. Both statements are true. But neither of us pointed out that the biases follow a significant pattern: midterm-year polling is far less accurate than Presidential-year polling.”

“From a practical standpoint, this is good news for those of you who don’t like where things have headed lately: in midterms, Senate polling errors are five times larger than in Presidential years. There is bad news too: the error can go in either direction, and a GOP blowout is also possible.”

First Read: “Between now and Election Day, you’re going to see a lot of divergent poll numbers. And the reason why is that not all likely voter models are created the same, even among good pollsters. We’re seeing more money being spent on turnout than ever before in a midterm cycle, but we’re also seeing American voters more turned off from the midterms than before. Those two things make polling more unpredictable. No one is confident who will be showing up to vote.”

Last week, Nate Silver wrote a lengthy critique of Sam Wang’s midterm election forecast for Political Wire.

Wang responds below.

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FiveThirtyEight asks pollsters for their thoughts on the midterm elections and the accuracy of polling.

“In their responses, most pollsters predict Republicans will win the Senate by a narrow margin. Many say fewer people are responding to polls this year, compared to 2012, and more expect greater polling error — that is, the difference between what the latest pre-election polls show and actual vote margins — in the upcoming election, than expect less error. And yet, the results also show how little the pollsters agree on.”

Exclusive to Political Wire, Nate Silver defends his critique of Sam Wang’s election forecast. It’s definitely worth reading.

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For those interested in what has become an epic battle of election forecasters, Sam Wang responds to Nate Silver’s extensive criticism of his midterm election forecasting model.

Sam Wang notes that “in any given year, approximately 10% of Alaska’s population has just arrived or is about to move away.”

“This is reminiscent of Nevada, which has very similar statistics. Nevada is also the site of a spectacularly wrong polling error. In fall of 2010, surveys unanimously showed Republican Sharron Angle favored to unseat Democratic Senator (and Majority Leader) Harry Reid, by a median of four percentage points. Every data-based prognosticator, including me, expected Angle to win. Yet Reid won the election by 5 points, outperforming polls by 9 points. I regard this as the worst miss of Senate polling in the last three election cycles.”

“Based on the extreme mobility of Alaska residents, I suggest a problem of potentially far larger impact. Like Nevada, telephone-based surveys in both states simply fail to capture a sample that is fully representative of voters. In other words, I suggest that ideologically diverse states with lots of recent arrivals are subject to inaccuracy.”

Nate Silver: “I don’t like to call out other forecasters by name unless I have something positive to say about them — and we think most of the other models out there are pretty great. But one is in so much perceived disagreement with FiveThirtyEight’s that it requires some attention. That’s the model put together by Sam Wang, an associate professor of molecular biology at Princeton.”

“That model is wrong — not necessarily because it shows Democrats ahead (ours barely shows any Republican advantage), but because it substantially underestimates the uncertainty associated with polling averages and thereby overestimates the win probabilities for candidates with small leads in the polls.”

Kevin Drum: “If Wang’s prediction of this year’s Senate race turns out to be more accurate than Silver’s, I almost hate to think what might happen. Silver’s head is going to explode or something. In any case, this is far more fun than you normally get from a couple of geeky poll aggregators.”

Nate Silver: “There is no shortage of reasons to worry about the state of the polling industry. Response rates to political polls are dismal. Even polls that make every effort to contact a representative sample of voters now get no more than 10 percent to complete their surveys — down from about 35 percent in the 1990s.”

“And there are fewer high-quality polls than there used to be. The cost to commission one can run well into five figures, and it has increased as response rates have declined.1 Under budgetary pressure, many news organizations have understandably preferred to trim their polling budgets rather than lay off newsroom staff.”