@misc{Riv15x,
  author =      { Ronald L. Rivest },
  title =       { DiffSum---A Simple Post-Election Risk-Limiting Audit },
  date =        { 2015-09-01 },
  OPTyear =     { 2015 },
  OPTmonth =    { September 1, },
  howpublished = { arXiv:1509.00127 },                  
  urla =        { <a href="http://arxiv.org/abs/1509.00127">arXiv</a> },
  abstract =    { This paper presents DiffSum, a simple post-election
                  risk-limiting ballot-polling audit for two-candidate
                  plurality elections. DiffSum sequentially draws
                  ballots (without replacement) until the numbers $a$,
                  $b$, of votes for candidates $A$, $B$ satisfies
                  $a>b$ and $(a-b)^2 > c(a+b)$, where $A$ is the
                  reported winner and $c$ is a suitably chosen
                  constant. Bounds on the error rate (chance of
                  approving an incorrect election outcome) are
                  obtained via simulations. The method is compared
                  with the Bravo method of Lindeman, Stark, and
                  Yates.},
}