Maréchal criterion

The Maréchal criterion is a guideline used in industrial design, particularly in optics and acoustics, to determine the acceptable quality of products. It states that the distribution of tolerances—variations in dimensions allowed in manufacturing—should be controlled in a way that minimizes the risk of defects. Specifically, it suggests that a small percentage of very badly produced items can be tolerated if the majority meet quality standards. Essentially, it balances cost-efficiency in production with maintaining a level of quality that satisfies customers, ensuring that the final product performs reliably while keeping expenses reasonable.