In political studies, surveys have been conducted in order to construct historical rankings of the success of the presidents of the United States. Ranking systems are usually based on surveys of academic historians and political scientists or popular opinion. The scholarly rankings focus on presidential achievements, leadership qualities, failures and faults. Popular-opinion polls typically focus on recent or well-known presidents. General findings Abraham Lincoln, Franklin D. Roosevelt, and George Washington are most often listed as the three highest-rated presidents among historians. More recent presidents such as Ronald Reagan and Bill Clinton are often rated among the greatest in public opinion polls, but generally do not rank as highly among presidential scholars and historians. Because William Henry Harrison and James A. Garfield both died within their first year in office, they are often omitted from presidential rankings. Zachary Taylor died after serving as president for only 16 months, but he is usually included. In the case of these three presidents, it is not clear whether they received low rankings due to their actions as president or because each was in office for such a limited time that they did not accomplish much. Political scientist Walter Dean Burnham noted the "dichotomous or schizoid profiles" of presidents, which can make some hard to classify. Historian Alan Brinkley stated that "there are presidents who could be considered both failures and great or near great (for example, Nixon)". Historian and political scientist James MacGregor Burns observed of Nixon: "How can one evaluate such an idiosyncratic president, so brilliant and so morally lacking?" It's also not clear that the absolute rankings mean much, especially for the middling presidents. Gerard Baker, US editor for The Times, writes, "the 42 American presidents fall into a well-established, Bell-curve or normal distribution on a chart – a handful of outstanding ones, a handful of duds, and a lot of so-sos. I couldn't, in all honesty therefore, really say that number 13 on the list is that much better than number 30." History A 1948 poll was conducted by historian Arthur M. Schlesinger Sr. of Harvard University. A 1962 survey was also conducted by Schlesinger, who surveyed 75 historians. Schlesinger's son, Arthur M. Schlesinger Jr., conducted another poll in 1996. The Complete Book of U.S. Presidents also gives the results of the 1982 survey, a poll of 49 historians conducted by the Chicago Tribune. A notable difference from the 1962 Schlesinger