Reply #3: Typical engineers... blame the user.

[parasim]

My guess is that they aren't employing any usability experts for these things.

I mean, you've got say, two buttons 5 pixels apart. So, the name of the candidate is at the top of the button, close to the top edge. That means the candidates name is within 10 pixels or so of the other button above it.

So, the user intends to select the candidate in the second button and will typically touch the candidates name, not the center of the button. Ok, so if the calibration is off by 10 pixels then the top button is selected.

Usability prinicples (such as Fitt's Law) would dictate that you should put the name of the candidate in the center of the button, so even if the calibration is slightly off, the intended candidate will be selected.

On top of the that, these machines could be fitted with high quailty touchscreens (like on the iPhone) that only activate if touched by skin, negating any extraneous things like jewelry, fingernails, etc. that could cause a wrong selection.

Basic stuff here.