In 1936, the Literary Digest conducted what was then one of the largest and most expensive polls of all time. With a sample size of nearly 2.4 million people sourced from subscription lists, telephone directories, and club rosters, the esteemed magazine predicted that Alfred Landon, the Republican governor of Kansas, would win the presidential election by a 14-point margin over the incumbent Franklin Roosevelt. “When the last figure has been totted and checked,” the Digest’s editors wrote in August of that year, “the country will know to within a fraction of 1 percent the actual popular vote of forty million [people].”

Three months later, however, they proved to be dead wrong. Roosevelt won the popular vote by more than 24 points in what is now remembered as one of the greatest political landslides on record. The Literary Digest poll has since gone down in history as a cautionary tale of sampling bias pitfalls, and is taught in intro-level statistics classes. Even the infamous 1948 election polls, known as the “Dewey Defeats Truman” disaster, did not fail quite so horribly as the Literary Digest in 1936.

Eighty years later, the polling industry was well overdue for a crash and burn of equal scale. In his final projections before the presidential election, the Princeton Election Consortium’s Sam Wang gave Hillary Clinton a whopping 99 percent probability of winning. The New York Times, meanwhile, put her at 85 percent. Of the ten major polls averaged by RealClearPolitics, eight predicted she would win by a margin of at least three points. Not even the respective campaigns’ internal polls foresaw a Donald Trump victory, which only became clear at around 8:30 p.m. on November 8. “We all estimated the Clinton win at being probable, but I was most extreme,” admitted Wang, who fulfilled his promise to eat a bug on live television after Trump won. “Polls failed, and I amplified that failure.”



Even the political betting markets—once hailed by economists as the new frontier of predictions for integrating all available polling data, analysis, and other information—were blindsided. They were supposed to play the long game: While the polls were a snapshot of what people were thinking in a particular moment, the markets were more focused on what would happen in the future.

But the markets had two major failures this year: first, Brexit and then Trump. In the days before the British referendum to leave the European Union, PredictIt reported that shares were only trading at 27 cents on the probability of an exit. And at 8:13 p.m. on election night, Clinton’s stock saw an all-time high of 94 cents. That fell to below 50 cents by 9:50 p.m. and to a penny by 1:44 a.m. the following morning.

