Chapter 2 notes, ideas and concepts. In addition, what is the relationship between spec limits, and the natural process variation based upon either a known or estimated population mean and population standard deviation.
Control charts have specific form to include upper and lower control limits, and center lines.
Once set-up and operational and stable, they allow basis for action either based upon out of control points, or trends and runs. The xbar chart is used to analyze the average level of a process, and the R chart is used to analyze its spread or dispersion. They indicate whether or not the process is stable, whether a constant system of chance causes appears to be operation. A picture is worth a thousand words , management by data. Sections 2.2 pg 38, and 2.2.1 provide a basis for creating and using the charts.