Abstract
Assuming the profit to be the unique measure of overall performance of a firm, the paper discusses the necessity of using "opportunity loss" as the performance scale in lieu of traditional "realized versus planned profit difference", and explains profit concepts needed to calculate opportunity losses for departmental performances as well as the total performance of the firm. The concenpts are "ex post optimal" profits for each department and for the firm as a whole. With these concepts are explained the partial opportunity losses for departments against the total opportunity loss for the firm.
