Hi all
I've recently developed an app to easily produce SPC charts with mean, +1 sigma, UCL lines etc. To take this further I've been asked to highlight data points that meet the following rules. The first one is easy enough, but some of them are quite complex. Has anyone else developed something similar?
Thanks in advance
Adam
| Observation | Interpretation |
A | A single point beyond a control limit | A special cause, or a very large shift in the process mean and/or variation |
B | 9 consecutive points on one side of the average | A small shift in the process mean and/or variation |
C | 6 consecutive points trending up or down | A shifting process mean |
D | 14 consecutive points alternating up & down | A systematic up & down pattern |
E | 2 of 3 consecutive points beyond 2 sigma (the warning limit) | A large shift in the process mean and/or variation |
F | 4 of 5 consecutive points beyond 1 sigma (first deviation) | A medium shift in the process mean and/or variation |
G | 15 consecutive points within 1 sigma (first deviation) | A reduction in the process variation (more consistent than normal) |
H | 8 consecutive points outside both +1 sigma and -1 sigma | The process is more volatile than normal |
