Accuracy of Assignments
Assigning costs accurately to cost objects is crucial.Accuracy is not evaluated based on knowledge of some underlying “true” cost. Rather, it is a relative concept and has to do with the reasonableness and logic of the cost assignments methods used. The objective is to measure and assign, as well as possible, the cost of the resources consumed by a cost object. The
Some cost assignment methods are clearly
more accurate than others. For example, suppose you want to determine the cost of
lunch for Elaine Day, a student who frequents Hideaway, an off-campus pizza parlour. One cost assignment approach is to count the number of customers at the
Hideaway between 12:00 P.M. and 1:00 P.M. and then divide that into the total sales
receipts earned by Hideaway during this period. Suppose that this comes to $6.25
per lunchtime customer. Based on this approach we would conclude that Elaine
spends $6.25 per day for lunch. Another approach is to go with Elaine and observe
how much she spends. Suppose that she has a chef’s salad and a medium drink each
day, costing $4.50. It is easy to see which cost assignment is more accurate. The
$6.25 cost assignment is distorted by the consumption patterns of other customers
(cost objects). As it turns out, most lunchtime clients order the luncheon special for
$5.95 (a mini-pizza, small salad, and medium drink).
Distorted cost assignments can produce poor decisions. For example, if a plant
manager is trying to decide whether to continue producing power internally or to
buy it from a local utility company, then an accurate assessment of how much it is
costing to produce the power internally is fundamental to the analysis. If the cost of
internal power production is overstated, the manager might decide to shut down the
internal power department in favour of buying power from an outside company,
whereas a more accurate cost assignment might suggest the opposite. It is easy to see
that poor cost assignments can prove to be costly.