Centre Line (CL)
Reference level of a control chart — mean of observations or subgroup means.
Also known as: CL, centreline, centerline
The centre line CL of a control chart represents the current process level. Its control limits sit ±3σ around it.
- Variables charts (X̄-R, X̄-S) — CL = (grand mean of subgroup means)
- Individuals chart (I-MR) — CL = on the I chart, on the MR chart
- p chart — CL = (average fraction defective)
- c chart — CL = (average defects per unit)
See also
Used in
In the Algorithm Lab
Sources
- Shewhart, W. A. — Economic Control of Quality of Manufactured Product, 1931
- Montgomery, D. C. — Introduction to Statistical Quality Control, 8th Edition