Nate Silver: Models Based on ‘Fundamentals’ Have Failed at Predicting Presidential Elections

Nate Silver is an American statistician and a blogger for the New York Times.

The 1988 presidential election was a victory for political science. Michael Dukakis had led George Bush in the polls for much of the spring and summer. But Mr. Bush had some fundamental advantages — the economy was sound, and he was the vice president to a popular incumbent, Ronald Reagan. As the fall came, Mr. Dukakis’s numbers wilted, and Mr. Bush captured a decisive victory, winning 426 electoral votes and taking the popular vote by about nine percentage points.

The election came at a time when political scientists and economists were interested in evaluating the relationship between economic performance — sometimes along with other “fundamental” (if harder-to-quantify) factors like war — and the fate of incumbent presidents.

This had long been something of a controversial subject. The elections of 1948 through 1968 had been a quirky lot. Foreign policy — the aftermath of World War II and the wars in Korea and Vietnam — had played an unusually important role. There were sometimes wide disparities in the strength of the candidates, with parties nominating figures as compelling as Dwight D. Eisenhower or as far from the center of the electorate as Barry M. Goldwater. There were other quirky circumstances: Lyndon B. Johnson and Harry S. Truman had succeeded deceased presidents in midterm and won a full term of their own, but refused to run for a third term even though they were eligible for one. The modern primary system was gradually developing, and television was becoming more widespread.

Whatever it was about this period, the relationship between elections and the economy seemed to be very weak — and, in fact, often seemed to run in the opposite direction of what we might expect. The incumbent party had won in 1948 and 1956 despite a middling economy but lost in 1952 and 1968 despite a pretty good one.

Nevertheless, some economists and political scientists asserted, there was a relationship between the economy and elections in the long term. In 1978, the Yale economist Ray C. Fair published a well-known paper that looked to data as far back as the 1890s to make the case. The relationship between the economy and elections wasn’t particularly strong — it could be overridden by war, scandals and other factors — and the quality of the data was mixed. But there seemed to be something there if one looked carefully enough....

But is it true? Can political scientists “predict winners and losers with amazing accuracy long before the campaigns start”?

The answer to this question, at least since 1992, has been emphatically not. Some of their forecasts have been better than others, but their track record as a whole is very poor....