In the course of time, the tools put at the service of quality evolved/moved a lot. In the beginning, they were primarily controls aiming at separating the good products from bad. To optimize control thus amounts to determining points of judicious control. Then, it was in the Thirties that industrial use of statistics started to develop with control by sampling.
But it is to better prevent than to cure and, rather than remarking the condition of the product at its exit, it is preferable to make sure at each production stage the product’s quality. It is the quality assurance: the need to make sure that there is a constant quality. According to DUPONT (1998), "the quality assurance does not guarantee the batch which has just been manufactured to any given quality. It guarantees that the existing organization gives the company the capacity to ensure the duration the production of such batches "(my translation).Control and quality assurance are thus essential but constitute only two of the tools in the steps towards total quality. Indeed, quality must be total and imply the company as a whole.Control and quality assurance are thus essential but constitute only two of the tools of a step towards total quality. Indeed, quality must be total and imply the company as a whole. Total quality is a whole of principles and methods organized in total strategy, aiming at mobilizing all the company (with its partners) to obtain a better satisfaction of the low cost requirements.