Does voting machine technology affect the outcome of elections?
Some interesting results found in a study of 2000-2004 election data.
We first show that there is a positive correlation between use of touch-screen voting and the level of electoral support for George Bush. This is true in models that compare the 2000-2004 changes in vote shares between adopting and nonadopting counties within a state, after controlling for income, demographic composition, and other factors. Although small, the effect could have been large enough to influence the final results in some closely contested states.
They also found:
Touch-screen voting could also indirectly affect vote shares by influencing the relative turnout of different groups. We find that the adoption of touch-screen voting has a negative effect on estimated turnout rates, controlling for state effects and a variety of county-level controls.