Dynamic Nature of Quality Costs The discovery that trade-offs among quality cost categories can be managed differently from what is implied by the relationships portrayed in Exhibit 15-5 is analogous to the discovery that inventory cost trade-off can be managed differently from what the traditional inventory model (EOQ) implied Essentially, what happens is that as firms increase their prevention and appraisal cost and reduce their failure costs, they discover that they can then cut back on the prevention and appraisal costs. What initially appeared to be a trade-off turns out to be a permanent reduction in costs for all quality cost categories. Exhibit 15-6 displays