On August 15th, 2004, Venezuelans had the opportunity to vote in a Presidential Recall Referendum to decide whether or not President Hugo Chávez should be removed from office. The process was largely computerized using a touch-screen system. In general the ballots were not manually counted. The significance of the high linear correlation (0.99) between the number of requesting signatures for the recall petition and the number of opposition votes in computerized centers is analyzed. The same-day audit was found to be not only ineffective but a source of suspicion. Official results were compared with the 1998 presidential election and other electoral events and distortions were found.
Gustavo Delfino. Guillermo Salas. "Analysis of the 2004 Venezuela Referendum: The Official Results Versus the Petition Signatures." Statist. Sci. 26 (4) 479 - 501, November 2011. https://doi.org/10.1214/08-STS263