Of all the quality tools which are used in industry today Taguchi’s Quality Loss Function is one of the most under used and underappreciated tools for improving product quality.   This tool should be in every process engineer’s arsenal when a cost justification is necessary to improve a particular process, or if it would be beneficial to determine a cost/benefit analysis before moving towards process improvements.  The concept is quite simple.  As you move away from an optimum design target, the loss to a customer increases exponentially.