Control phase of DMAIC
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…)
Acceptance sampling explained: single, double and sequential plans, AQL, LTPD, producer’s and consumer’s risk, OC curve with a worked example, and Z1.4.
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.
Attribute chart: c chart is also known as the control chart for defects is generally used to monitor the number of defects in constant size.
Attribute chart: u chart is the control chart for defects per unit. It is used to monitor the count type of data where the sample size is>1.