zonesix

Learn to read a control chart

Start with an example to see what control charts reveal about a process, then try your own data.

How we calculate

Process sigma estimated via average moving range with d2 bias correction. Control limits set at 3σ from the process mean. Capability indices use sigma-within (Cp/Cpk) and sigma-overall (Pp/Ppk). Results validated against R’s qcc package. Reference: Montgomery, Introduction to Statistical Quality Control.