Accounting textbooks generally say that the decision to accept a special order should be based on the “relevant” or avoidable costs of filling the order, not the normally computed full costs of production. The full costs include some fixed costs per unit. Studies of managers typically show that they are very reluctant to price anything at a level below the full costs. To put it another way, the evidence is that most managers do not follow the textbook advice to ignore fixed costs in short-term pricing decisions.

Can you suggest reasons why managers do not follow the textbook advice?