In my DSP classes I often cover the difference between precision and accuracy when measuring and processing input values from a transducer.
I recently came across an excellent little illustration of this on page 7 of the Keller-Druck Brochure : http://flipflashpages.uniflip.com/2/52802/96120/pub/#page7.
From a signal processing point of view the key points from this diagram are :
1/ When the measurements are very precise (as shown in diagram A) then accuracy can be improved by removing the offset via subtraction of the average of the samples.
2/ When measurements are more accurate but there is a larger deviation (as shown in diagram B) then the deviation can be reduced by oversampling and averaging the results.