Risk-based control chart

A risk-based control chart extends the classical Shewhart control chart by explicitly incorporating the costs and probabilities of two error types — false alarms (Type I) and missed shifts (Type II) — along with sampling costs, into the design of chart parameters. Rather than using arbitrary 3-sigma limits, the method selects sample size, sampling interval, and control limits to minimise the total expected cost or risk of operating the monitoring scheme.