Here enters the concept of counting tolerance. Items such as fasteners are normally not hand counted but scale counted. (The stock is weighed, and then translated into pieces by a conversion factor.) If, for example, the scale is accurate to plus or minus 2 percent, and/or the parts vary a bit in weight, then it obviously isn’t practical to insist on an exact match of the count to the book record. In cases where items are weigh counted (or volume counted, such as liquids in a tank), companies assign a counting tolerance to the item. In the example above, the counting tolerance might be plus or minus 3 percent. Any physical count within plus or minus 3 percent of the computer record would be considered a hit, and the computer record
would be accepted as correct.