Trump and Sanders Test Economic Model Predicting a G.O.P. Win
By JEFF SOMMER

If this were anything like a normal year, the Republicans would be favored to take the White House. That, at least, is what Ray Fair’s economic model has been saying consistently since November 2014.

Mr. Fair, a professor of economics at Yale and the author of “Predicting Presidential Elections and Other Things,” also says his model may well be wrong about this election. “Each election has weird things in it, yet the model usually works pretty well,” he said. “This year, though, I don’t know. This year really could be different.”

Professor Fair has been tracking and predicting elections in real time since 1978 with a good deal of success, using an approach that continues to be provocative. He ruthlessly excludes nearly all the details that are the basic diet of conventional political analysts — items like the burning issues of the day, the identities, personalities and speeches of the candidates and the strength of their campaign organizations. In fact, his model pays no attention whatsoever to the day-to-day fireworks of the political campaigns.

Instead, he considers only economics, finding that economic factors usually correlate well with political outcomes. Using two open-source econometric models that he posts on his website, he first estimates the strength of the economy. He uses that economic analysis to predict the popular vote for the two main parties, the Democrats and the Republicans. He comes up with his first estimate two years before the presidential election and provides updates at regular intervals.

In November 2014, he did his first projection for the 2016 election and found that the odds favored the Republican candidate — whoever that may be. The Republican side has been leading consistently ever since, and the margin has increased as he has fed in new data.

From the blinkered viewpoint of the model, which sees the world through a narrowly focused economic lens, the problem, for the Democrats, starts with a handicap that is built into the equations: A two-term incumbent is in the White House. When that is the case, the opposition party has a roughly three-percentage-point edge, which can be surmounted fairly easily if the economy is quite strong. That’s because historical data suggests that an incumbent president tends to be blamed for a bad economy and receive credit for a good one, Professor Fair says. That blame or credit spills over to the candidate from the president’s own party.

This time around, while the economy is not in recession, it is not particularly strong either, using the main criterion favored by Professor Fair. That is the rate of growth of real per capita gross domestic product. He estimates that for the nine months leading to this November’s election, that growth rate, on an annualized basis, will be just under 2 percent, roughly in line with consensus forecasts. A growth surge could change the results of the model, but right now that doesn’t seem likely, he said.

In his latest update, done in late January, the spread exceeded the model’s margin of error, suggesting that the ultimate Democratic Party candidate will have an uphill climb.

“That’s what the model shows,” Professor Fair says. And the economic backdrop is worth noting, he says, though he’s not certain how accurate the model will turn out to be this year. Clearly, the factors that Professor Fair excludes do matter. What’s interesting is that often, the economy matters more.

Consider the limits of the model itself. It has worked reasonably well in most elections since 1980, and it performs well in back-tested analyses of elections since 1916, but it is far from infallible, even in achieving its goal: a prediction of the popular vote for the two main parties. If there is a third candidate (or a fourth) in the general election, the model doesn’t acknowledge the candidate’s existence, in effect assuming that the two traditional parties are affected equally. That assumption may not be correct.

It probably was incorrect in the 1992 election, a terrible one for the model, which predicted that President George H. W. Bush would be re-elected. Ross Perot received 19 percent of the vote, probably hurting President Bush in ways not captured by the model, Professor Fair says. That was also the election in which the campaign of the victor, Bill Clinton, relied on the mantra, “It’s the economy, stupid,” which could also be the slogan for Professor Fair’s model. He tweaked the model after that election, emphasizing economic factors even more. That was the last time he altered the model.

I asked Professor Fair whether he believed that he should alter the model again, to accommodate factors like the personalities of the candidates, and the polarization and potential fracturing of the two political parties. What if voters this year cross party lines in larger numbers than usual? What if the two-party alignment is being transformed into something new?

“The model might not pick any of that up,” Professor Fair said. “I think we’ll have to wait and see how it does. Even if the model is off this year, I might not change it. The economy will continue to be important. It’s possible this is simply a unique year.”

從經濟狀況分析大選 耶魯教授掐指共和黨贏

紐約時報報導， 倘若今年和一般正常總統選舉年無異，根據耶魯大學經濟學教授費爾（Ray Fair）著名的選舉預測模型，今年應是共和黨候選人入主白宮。

費爾說，每次選舉都有怪事發生，然而他的經濟預測模型仍堪稱準確，唯獨今年大選，「我不知道，今年或許真會失準」。

費爾從1978年開始即時追蹤和預測美國大選，儘管他的作法爭議性頗高。有別於傳統政治分析家，費爾絲毫不理會每天的政治選戰火花，不理會當天話題、候選人身分、個性、演說、選戰組織實力這些細節。他的預測模型幾乎只考慮經濟一項因素，認為經濟通常與政治結果息息相關。

利用他網站上兩個計量經濟模型，費爾先是預測經濟強度，再利用所得的經濟分析結果，預測民主、共和兩黨的普選票票數。他會在大選兩年前公布第一次預測，其後定期更新預測。他用這套模型回推到1916年的總統大選，都正確無誤。

不過，從1980年來，費爾的模型預測錯過兩次，一次是1992年，獨立參選的培洛拿下19%普選票，導致預測失準。另一次是2012年，他預測競選連任的歐巴馬只能拿到49%普選票，結果歐巴馬拿到52%，不過費爾強調3個百分點的差距在誤差範圍內。

前年11月，費爾公布2016年大選首次預測，指出形勢有利共和黨候選人，無論何人代表共和黨出征。共和黨其後一路看好，在他添加更多新資料後，差距還持續擴大。

根據費爾的預測模型，由於在位的政黨是連任，必須讓分約3個百分點，因為根據歷史資料，經濟欠佳，選民會歸咎現任者。若經濟強勁，這項讓分可輕易克服。目前美國經濟並不特別強勁，費爾預估未來9個月經濟成長略低於2%，此數字與一般預測相同。根據費爾的模型，除非經濟成長率衝上4%，民主黨才會贏。但就目前觀察，經濟成長勁揚的可能性極低。

上述的差距仍大於模型的預測誤差，意謂民主黨候選人最終將有一番苦戰。費爾說：「模型是這麼顯示的。」他說，經濟變化值得注意，儘管他不確定今年模型是否準確。

不過，費爾模型未列入考量的候選人身分、個性等因素，在今年美國大選似乎變得至關重要，因為在共和黨初選領先的川普，是美國大選中許久未見的爭議人物。

原文參照：
http://www.nytimes.com/2016/03/20/your-money/trump-and-sanders-test-economic-model-predicting-a-gop-win.html

2016-03-21．聯合報．A13．兩岸/國際．編譯王麗娟