Unformatted text preview: and LCL is lower control limit, or lowest possible value that we’d consider to indicate a process in control. 3. Why do you suppose ±3 standard errors are used in control charts and not two standard errors or even one standard error? I think any standard error could be used, because when using ±3 standard deviation =99.73%; it falls within the 3-sigma limits 4. Explain the four rules of thumb for identifying an out-of-control process. Rule 1- Single point outside 3 sigma. Rule 2- Two of three successive points outside 2 sigma on same side of centerline. Rule 3- Four of five successive points outside 1 sigma on same side of centerline. Rule 4- Nine successive points on same side of centerline...
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- Spring '10
- Control Chart, LCL, Successive Points