  This study analyzes diverse hypotheses of electronic fraud in the Recall
Referendum celebrated in Venezuela on August 15, 2004. We define fraud as the
difference between the elector's intent, and the official vote tally. Our null
hypothesis is that there was no fraud, and we attempt to search for evidence
that will allow us to reject this hypothesis. We find no evidence that fraud
was committed by applying numerical maximums to machines in some precincts.
Equally, we discard any hypothesis that implies altering some machines and not
others, at each electoral precinct, because the variation patterns between
machines at each precinct are normal. However, the statistical evidence is
compatible with the occurrence of fraud that has affected every machine in a
single precinct, but differentially more in some precincts than others. We find
that the deviation pattern between precincts, based on the relationship between
the signatures collected to request the referendum in November 2003 (the
so-called, Reafirmazo), and the YES votes on August 15, is positive and
significantly correlated with the deviation pattern in the relationship between
exit polls and votes in those same precincts. In other words, those precincts
in which, according to the number of signatures, there are an unusually low
number of YES votes (i.e., votes to impeach the president), is also where,
according to the exit polls, the same thing occurs.
