"‘Vote Flipping’ Is Real, but Its Cause Is the Subject of Debate"

Computerworld has an article, "'Vote Flipping" Is Real, but Its Cause Is the Subject of Debate" that says that the problem might be user error where voters are "accidentally touching a screen and erroneously making a selection". David Dill rules out conspiracy because the votes are being shown to the voter, if there was a conspiracy to change votes then the vote selection would be incorrectly shown to the voter. The article also states that researchers have found that voters incorrectly mark their ballots one in 30 times, even under laboratory conditions. Another possible problem is machine calibration, where the machines are sensitive to voter height, angle of touch and other factors.