HITEQUEST
technical interviews for high-tech professionals

=Brainstorming technical problems=

Benjamin.
The inaccuracy of your measurements results from systematic errors (gain error, offset error, non-linearity) and random errors (quantization error, noise). If the goal of your experiment is to find out how the voltage differs between the points relatively to each other then you definitely need to go with one instrument. This will reduce the systematic error. For example if your meter is consistently off by 10mV (have not been calibrated for a long time). In case you are interested in absolute values then the idea with one instrument doesn't help. You may have to take multiple measurements and average the results to get better accuracy.