Comments on: Introducing Control Charts (Run Charts) http://peltiertech.com/WordPress/introducing-control-charts-run-charts/ PTS Excel Charts and Tutorials Blog Sat, 21 Nov 2009 04:01:08 -0600 http://wordpress.org/?v=2.8.4 hourly 1 By: darman http://peltiertech.com/WordPress/introducing-control-charts-run-charts/comment-page-1/#comment-9276 darman Fri, 30 Jan 2009 06:23:36 +0000 http://peltiertech.com/WordPress/?p=66#comment-9276 does this Run CC build from runs test (non-par analysis)? does this Run CC build from runs test (non-par analysis)?

]]> By: Validate Your Tables with Micro (Control) Charts | More Information per Pixel http://peltiertech.com/WordPress/introducing-control-charts-run-charts/comment-page-1/#comment-2667 Validate Your Tables with Micro (Control) Charts | More Information per Pixel Wed, 06 Aug 2008 08:34:19 +0000 http://peltiertech.com/WordPress/?p=66#comment-2667 [...] just by quickly scanning the shape. Let’s add a bit more science. In another post Jon showed that Control Charts can be used to identify [...] [...] just by quickly scanning the shape. Let’s add a bit more science. In another post Jon showed that Control Charts can be used to identify [...]

]]> By: Jon Peltier http://peltiertech.com/WordPress/introducing-control-charts-run-charts/comment-page-1/#comment-560 Jon Peltier Thu, 01 May 2008 18:48:43 +0000 http://peltiertech.com/WordPress/?p=66#comment-560 Hi Damir - The preferred approach is to calculate the mean and variation parameters (e.g., SD) at a point where the process has stabilized, that is, the process is in control. You then plot these values as the horizontal lines in the control chart, and don't change them until the process is knowingly changed. The dynamic control chart that this article links to calculates these parameters on all values in the chart, so if more observations are added, the parameters are recalculated. This is incorrect, as I designed that chart before I had been deeply involved in SPC-related activities. Hi Damir -

The preferred approach is to calculate the mean and variation parameters (e.g., SD) at a point where the process has stabilized, that is, the process is in control. You then plot these values as the horizontal lines in the control chart, and don’t change them until the process is knowingly changed.

The dynamic control chart that this article links to calculates these parameters on all values in the chart, so if more observations are added, the parameters are recalculated. This is incorrect, as I designed that chart before I had been deeply involved in SPC-related activities.

]]> By: Damir http://peltiertech.com/WordPress/introducing-control-charts-run-charts/comment-page-1/#comment-558 Damir Thu, 01 May 2008 18:13:28 +0000 http://peltiertech.com/WordPress/?p=66#comment-558 How do you calculate sigma when creating a control chart with UCL, LCL and sigma zones (+/- 1 to 3)? Is the sigma "locked"--meaning calculated on a batch of parts sometimes in past leading to constant LCL and UCL? Or, is it dynamically calculated which leads to LCL and UCL changing over time? If dynamically, how did (would) you deal with a process with SLOWLY increasing sigma (something getting loose on a machine)? How do you calculate sigma when creating a control chart with UCL, LCL and sigma zones (+/- 1 to 3)?
Is the sigma “locked”–meaning calculated on a batch of parts sometimes in past leading to constant LCL and UCL? Or, is it dynamically calculated which leads to LCL and UCL changing over time?
If dynamically, how did (would) you deal with a process with SLOWLY increasing sigma (something getting loose on a machine)?

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