The Great Predictor

摘要

Dr. Deming once said, "Variation is evil." All processes have variations, due to tool wear, operator differences, material quality, environmental factors, inconsistent information or documentation, and precision of equipment, among other things. Process capability is the ability of a process measured in terms of its variance. In statistical terms, it is measured in terms of three standard deviations around the process mean. To determine process capability, a process is characterized, and data are collected and analyzed to determine variance in terms of standard deviation. Process capability is determined after the process has been brought under statistical control using control charts. Once the process capability is determined, the predictor of the process performance is calculated and evaluated.