Control chart constants are the multipliers that turn an average range or an average standard deviation into 3-sigma control limits. They depend only on the subgroup size n. A2, D3 and D4 build the X-bar and R chart. A3, B3 and B4 build the X-bar and s chart. E2 and D4 (for n = 2) (more…)
Control chart rules explained: the Western Electric and Nelson rules, one clear rule set to use, and the false alarm trade-off of adding more rules.
Control charts are one of the hardest things for those studying six sigma to understand. Here’s an easy Control Charts Study Guide for you.
An Individual moving range chart (I-MR Chart) also called X-MR is used when data is continuous and not collected in subgroups (n=1).
Statistical process control (SPC) is a technique for applying statistical analysis to measure, monitor, and control processes.