In Search of the Black Swan: Analysis of the Statistical Evidence of Electoral Fraud in Venezuela

TL;DR

This paper investigates statistical evidence of electoral fraud in Venezuela's 2004 referendum, finding no evidence of machine-specific manipulation but suggesting possible precinct-wide irregularities correlated with signature and exit poll data.

Contribution

It provides a detailed statistical analysis testing hypotheses of electoral fraud, highlighting patterns consistent with precinct-wide irregularities rather than machine-specific tampering.

Findings

No evidence of machine-specific fraud was found.

Patterns of deviation correlate with signature and exit poll data.

Possible precinct-wide irregularities are suggested by the analysis.

Abstract

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.