"The statisticians found two telltale signs of massive tampering. In place of the single bell-shaped curve that would be expected to describe the distribution of votes obtained by each party, the PRI was found to have two such curves: one centered around a mean of 36 percent (its true national average), and the other peaking around an implausible 100 percent."
"A second diagnostic test revealed the provenance of these 'unanimous' results. Whereas totals for each of the opposition parties had last digits that occurred with roughly equal frequency, the last digit of PRI totals was 60 percent more likely to be a zero, indicating that the PRI had inflated its totals by simply adding zeros to its actual vote count."
А вот как Википедия резюмирует те мексиканские выборы:
"Years later, former president Miguel de la Madrid admitted to the New York Times and in an autobiography that the presidential elections had been rigged to make the Institutional Revolutionary Party win, and that three years after the election, all ballots were burnt in order to remove all evidence of the fraud."
http://en.wikipedia.org/wiki/Mexican_general_election,_1988