Dial calipers are more accurate if you place the workpiece close to the caliper. This reduces the Abbe error. The Abbe error on this caliper is .002 inch. This occurs because the caliper jaws are forced to bend outward. By placing the workpiece closer to the center axis of the caliper, the bending force is reduced and more accurate measurements will be taken.
The Abbe Principle can be used as one method of evaluating the quality of a dial caliper.