As explained in an earlier chapter, the terms mistakes and errors are NOT synonymous in surveying.

Leveling operations, like other survey measurements, are susceptible to both. Mistakes can be avoided by a well-arranged system of operation and by constant alertness by the survey party members. Checking, as described in some of the operations, will eliminate many possible areas of mistakes. Errors cannot be completely eliminated, but they can be minimized so that their effect on the survey accuracy will be small and within the tolerances permitted.