Which method is used to evaluate process data to determine if a process is under control?

Statistical Process Control (SPC) is the method specifically designed to evaluate process data and determine whether a manufacturing or business process is operating under control. It involves the use of statistical tools and techniques to monitor and control processes. By analyzing data collected from processes over time, SPC helps identify variations that may affect quality. A key component of SPC is the use of control charts, which visualize process data and indicate when a process is deviating from expected performance.

This method is critical in quality management as it allows organizations to maintain consistent output and minimize variations which could lead to defects. By regularly applying SPC, companies can make informed decisions based on data, rather than assumptions, to enhance process stability and quality.

Other methods mentioned, such as Quality Control, Operational Analysis, and Variable Analysis, serve different purposes within the realm of quality and operations management but do not specifically focus on the continuous monitoring and statistical evaluation of process control that SPC provides. Quality Control generally focuses on ensuring that the output meets certain standards, Operational Analysis looks at the efficiency and effectiveness of operations, and Variable Analysis deals with analyzing specific variables of interest but not necessarily in the context of ongoing process control.