368 / 879
•
Control limits
(= natural limits of the process = “voice of the process”) :
Process’s production
is not always identical
Normal distribution
(central limit theorem )
A point falls
outside the natural limits
special cause with certain
risk (0.27%)
Natural dispersion
Mean + 3
Mean - 3
Mean
> 99%
0.135%
0.135%
LCL
UCL
=
risk
=
risk
•
Analysis of control charts
To be checked.
Part 1
:
Introduction to
SPC
Part 2
:
Essential
concepts to
start with SPC
Part 4
Conclusion
Part 3
:
SPC in
practice
A
NALYZE
14. Control charts building: calculation of control limits
•
Thesis K. Gérard (2008)
Details of limits’
calculation
•
Book of M. Pillet,
Appliquer la Maitrise
Statistique des Processus
(2005)
•
ESTRO Practical exercise, Torino (2015)
•
T. Pawlicki, SPC for radiotherapy QA (2005)
Control lim
Control lim
Carte de contrôle des valeurs individuelles
-1,5%
-1,0%
-0,5%
0,0%
0,5%
1,0%
1,5%
2,0%
2,5%
3,0%
0
10
20
30
40
Patient number
Individual Value (%)
3 potential special causes
X
UCL
6 points
9 points
LCL
Monitored parameter
Data (chronological order)
Mean
common
causes
03/10/17