Monday, December 2, 2013

Eisenhower, MacArthur and the Fallacies of Statistical Sampling

David Hackett Fischer's Historians' Fallacies is one of my favorite books. It is insightful, witty, and humorous. In one such fallacy, one he labels "The Fallacy of Statistical Sampling" Fischer provides several examples of the error, including a 1936 Literary Digest prediction that Kansas Governor Alf Landon would defeat the incumbent Franklin D. Roosevelt in the upcoming presidential election. Of course, Landon did not win. In fact, he suffered the biggest defeat in our nation's history, with FDR capturing 98.5% of the electoral college. Fischer argues that the Literary Digest poll was not an accurate barometer of the electorate at large because its sample drew disproportionately from wealthier Americans. In hindsight this seems so obvious as to be silly to miss. Far away on the other side of the globe, in the Philippines, a forty-five year old Lieutenant Colonel named Dwight D. Eisenhower couldn't believe the results of the Literary Digest poll. However, his boss, General Douglas MacArthur gave great credence to the poll. Partially this resulted from wishful thinking on the general's part. He  despised the FDR and hoped to see him ousted from the White House. The other issue is that, according to Eisenhower's Diaries (edited by Robert H. Ferrell, 1981) MacArthur bet 1,000 pesos on the Kansas governor winning the election. Eisenhower tried to dissuade his chief from this delusion and showed evidence that Landon could not even carry his (both Alf's and Ike's) home state let alone carrying the country. Although Eisenhower did not pinpoint the specific flaw of the Literary Digest poll, he knew that the survey lacked a "proper index." (p 22) MacArthur would have none of it and called Ike and another staff officer who ridiculed the Literary Digest poll results as, "fearful and small-minded people who are afraid to express judgements that are obvious from the evidence at hand." (p.22) Eisenhower's reaction in his diary was to scrawl, "Oh hell." (p.22) Six weeks later, on November 15, 1936, the subject came up again. This time MacArthur felt cheated by Literary Digest. Not only was he out 1,000 pesos, but he became fearful that the administration would discover that he had bet against them, quite literally.