Did Illegal Overseas Absentee Ballots Decide the 2000 U.S. Presidential Election?

Although not widely known until much later, Al Gore received 202 more votes than George W. Bush on election day in Florida. George W. Bush is president because he overcame his election day deficit with overseas absentee ballots that arrived and were counted after election day. In the final official tally, Bush received 537 more votes than Gore. These numbers are taken from the official results released by the Florida Secretary of State's office and so do not reflect overvotes, undervotes, unsuccessful litigation, butterfly ballot problems, recounts that might have been allowed but were not, or any other hypothetical divergence between voter preferences and counted votes. After the election, the New York Times conducted a six-month investigation and found that 680 of the overseas absentee ballots were illegally counted, and almost no one has publicly disagreed with their assessment. In this article, we describe the statistical procedures we developed and implemented for the Times to ascertain whether disqualifying these 680 ballots would have changed the outcome of the election. These include adding formal Bayesian model averaging procedures to models of ecological inference. We present a variety of new empirical results that delineate the precise conditions under which Al Gore would have been elected president and offer new evidence of the striking effectiveness of the Republican effort to prevent local election officials from applying election law equally to all Florida citizens.The authors are deeply grateful to the many private citizens of every political stripe who sent us comments on this paper; also to Jim Alt, Barry Burden, James Honeker, Doug Rivers, and Jonathan Wand for helpful discussions; to Henry Brady for many suggestions; and to the National Science Foundation, the National Institutes of Aging, and the World Health Organization for research support. Software to implement the methods in this article is available at http://gking.harvard.edu.

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