The front-runner fallacy
The Atlantic - 11/16/2015
Of course, sometimes the early polls do get it right. Typically this happens in races with few competitors, as when then–Vice President Al Gore led the Democratic field throughout 1999, or in races with an overwhelming favorite, as Ronald Reagan was in 1979. William Mayer, a political scientist at Northeastern University, found that in contested primary races since 1980, front-runners polling at 34 percent or higher in September the year before the election went on to win the nomination six of eight times—but not one of the five front-runners who fell short of that threshold ultimately prevailed.