The NEP report stated that "the size of the average exit poll error ... was higher in 2004 than in previous years for which we have data" and that exit polling estimates overstated Kerry's share of the vote in 26 states by more than one standard error and overestimated Bush's share in four states by more than one standard error. It concluded that these discrepancies between the exit polls and the official results were "most likely due to Kerry voters participating in the exit polls at a higher rate than Bush voters". The NEP report further stated that "Exit polls do not support the allegations of fraud due to rigging of voting equipment. Our analysis of the difference between the vote count and the exit poll at each polling location in our sample has found no systematic differences for precincts using touch screen and optical scan voting equipment." A study performed by the Caltech / MIT Voting Technology Project concluded that "there is no evidence, based on exit polls, that electronic voting machines were used to steal the 2004 election for President Bush." This study was criticized for using data that had been corrected to match the official count, and thus "essentially analyzing rounding error". On December 5, 2004 Charles Stewart III of MIT released a revised report which, he said, used pre-corrected data. Two days later, however, Warren Mitofsky, who had overseen the exit polling, stated that the pre-corrected data were proprietary and would not be released. One paper (and a follow-up book) concluded that discrepancies in the exit polls were evidence that the election results were off, though others alleged this paper was unscientific. Following the 2004 election, researchers looked at ways in which polling methodologies might be flawed and explored ways to improve polling in the future. Racial discrimination Some of the issues described above have created problems for voters generally. Others, however, by accident or (it is charged) by design, have disproportionately affected racial minorities. For example, the U.S. Commission on Civil Rights determined that, in Florida in 2000, 54 percent of the ballots discarded as "spoiled" were cast by African Americans, who were only 11 percent of the voters. Another paper studied the residual vote rates of the election technology used and the distribution of those technologies among race and found that the percentage of spoiled votes did not disproportionally affect any particular race. Recounts