What's Wrong With Electronic Voting Machines?

An oldie, but goodie. Here's some of it:

Trust a computer to be inaccurate

Technology gets in the way of accuracy by adding steps. Each additional step means more potential errors, simply because no technology is perfect. Consider an optical-scan voting system. The voter fills in ovals on a piece of paper, which is fed into an optical-scan reader. The reader senses the filled-in ovals and tabulates the votes. This system has several steps: voter to ballot, to ovals, to optical reader, to vote tabulator, to centralised total.

At each step, errors can occur. If the ballot is confusing, some voters will fill in the wrong ovals. If a voter doesn't fill them in properly, or if the reader is malfunctioning, then the sensor won't sense the ovals properly. Mistakes in tabulation -- either in the machine or when machine totals get aggregated into larger totals -- also cause errors.

A manual system of tallying the ballots by hand, and then doing it again to double-check, is more accurate simply because there are fewer steps.

The error rates in modern systems can be significant. Some voting technologies have a 5% error rate, which means one in twenty people who vote using the system don't have their votes counted. A system like this operates under the assumption that most of the time the errors don't matter. If you consider that the errors are uniformly distributed -- in other words, that they affect each candidate with equal probability -- then they won't affect the final outcome except in very close races.

So we're willing to sacrifice accuracy to get a voting system that will handle large and complicated elections more quickly.

In close races, errors can affect the outcome, and that's the point of a recount. A recount is an alternate system of tabulating votes: one that is slower (because it's manual), simpler (because it just focuses on one race), and therefore more accurate.

Note that this is only true if everyone votes using the same machines. If parts of a town that tend to support candidate A use a voting system with a higher error rate than the voting system used in parts of town that tend to support candidate B, then the results will be skewed against candidate A.