Quality Management 2017

A NALYZE

5. Characterization of the data distribution

• Build the histogram of the data:

Part 1 :

 Examples of data distributions

Introduction to SPC

Truncated

Asymetric

Normal

Bi-modal

Part 2 :

 Understand the shape of your data distribution. Was it expected?

Essential concepts to start with SPC

• Studied case: normal distribution  Why? ✓ Most of radiotherapy processes follow a normal distribution. ✓ SPC’s traditional formulas: based on the hypothesis of a normal distribution. • Important comment: with certain precautions*, it remains possible to use SPC tools for non normal distributions (* no more link between limits of control charts and the  risk, no more link between capability and % of data out of specifications)

Part 3 :

SPC in practice

Part 4

Conclusion

03/10/17

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