On August 15, Venezuelans voted in a national referendum on whether to remove President Hugo Chavez. The (Chavez-run) government announced afterward that 58% had voted to keep Chavez in office. The opposition claimed fraud.
The election was held on electronic voting machines. Fortunately, the machines generated a voter-verified paper trail, so that there was some hope of recounting the ballots. Without a paper trail there could have been no recount, and Venezuelans would have had to take the result on faith, or reject it. With a paper trail, there is at least some evidence of how the votes were cast.
What evidence is there for fraud? The opposition says that the election results were inconsistent with exit polling, which they say went 58-42 in the other direction. That’s a big enough swing to raise eyebrows, but it’s hard to evaluate the accuracy of the exit polls based on the information available to me.
The opposition’s other claim is that the voting machines were programmed to cap the number of yes votes (i.e., anti-Chavez votes) recorded on each voting machine. In support of this, the opposition points to the data on machine-by-machine voting results, arguing that machines in the same polling place recorded the exact same number of yes votes too often, that is, more often than would have occurred by chance. That’s a claim that is amenable to statistical analysis. I’ll evaluate it in a future entry.