Phase I Quality Control Charts for Variables

Statistical quality control (SQC) is a set of interrelated tools such as statistical process control (SPC), design of experiments, acceptance sampling, and other tools that are used to monitor and improve quality. SPC is one of the tools included in SQC and consists of several tools useful for process monitoring. Quality control charts can be divided into two major categories: control charts for variables and control charts for attributes. SPC is very useful in any process related to the manufacturing, service, and retail industries. This set of tools consists of seven parts, often known as the magnificent seven: histogram or stem‐and‐leaf diagram, scatter diagram, check sheet, pareto chart, cause‐and‐effect diagram, defect‐concentration diagram, and control charts. A control chart is a simple but powerful statistical device used to keep a process predictable. The chapter discusses the concept of process capability.