In it, he suggests a simple cost evaluation model. It compares the cost of poka-yoke devices with the cost savings from defect elimination. Analysis Shigeo Shingo was one of the industrial engineers at Toyota who has been credited with identifying setup time reduction as a step in improving manufacturing flexibility and efficiency. Effective poka-yoke devices reduce the cost of inspection, making it economical to increase both the frequency and quantity of inspection. Same as an np-chart, lower inspection cost to near zero to make it more economical.
Analytic model is quite complicated.
If a self-check is desired, minimize inspection cost. If possible create a source inspection instead. Use to sort defects when cost of in-house quality problems is much less than cost of problems at the customers' facility. Make sure to minimize inspection cost. If possible create a source inspection instead.