Quality Management 2017
A NALYZE
13. Control charts building: EWMA
Type of drifts to detect
Control charts
Part 1 :
Introduction to SPC
Ex.: wrong adjustment of linac’s parameters, errors during measurement…
Large and Fast
Individual value / Moving Range Individual value o i nge
(I,MR)
Part 2 :
Patient number
Diff. mes/calc. (%)
Essential concepts to start with SPC
EWMA - Exponentially Weighted Moving Average -
Ex.: drift of the detector’s dose response
Small and slow
Part 3 :
Patient number Diff. mes/calc. (%)
SPC in practice
4%
EWMA control chart
N ° patient
3%
EWMA control chart
2%
coefficient
coefficient
Part 4
1%
1i ) 1( x M M
Conclusion
i
i
0%
EWMA
-1%
Résultat en cours
Historique des données
-2%
-3%
Patients #
03/10/17
33
2
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