The cumulative effect of prevention

Quality costs have been discussed widely in the literature. This discussion has not always agreed and it is possible to identify two basic schools of thought; one asserts the existence of a minimal level of quality cost for a given level of prevention and appraisal activities, and the other asserts that through prevention quality improvement is constant. This paper summarises these positions and outlines a behaviour model of quality costs that unifies and clarifies them. The behaviour model is based on the consideration of the cumulative effects of prevention. Ceteris paribus, continuous prevention activities should permit quality improvements whilst at the same time reducing the costs necessary to obtain them. The behaviour model introduces the effect of external quality requirements in an attempt to explain how, over time, quality improvement efforts do not necessarily result in decreased quality costs as customers’ quality requirements rise over the same period.