Statistical Tools outside of SPC

[Internet-101]

Could somebody tell me if there are some Statistical Tools outside of SPC? But those are recognized and validated by QS-9000.
And how is the best way to find and use them?

Thanks

Smile is good for your health!

 

[Al Dyer]

Anything with a numerical value could be considered a "statistic" while not being Statistical Process Control. Also, QS-9000 does not validate or recognize specific statistical methods. Except for capability studies in APQP/PPAP QS-9000 only says to identify the need for statistics and have process control. I believe the only place SPC is mentioned is 4.20.4 where it says to reference the AIAG SPC manual for guidance on knowledge of statistical concepts.

Hope I haven't put my foot in my mouth again!

 

[KenK - 2009]

I have to correct your statement Al.

The 3rd edition of QS-9000 does indeed have specific requirements regarding the statistical methods used for measurement system analysis and capability analysis:

MEASUREMENT SYSTEMS ANALYSIS
Element 4.11.4: "The analytical methods and acceptance criteria used should conform to those in the Measurement Systems Analysis reference manual (e.g. bias, linearity, stability, repeatability and reproducibility studies). Other analytical methods and acceptance critieria may be used if approved by the customer.

What that means is, use the specific methods in the MSA book, or have your customer approve alternative methods in writting (we tend to avoid specific customer-approved waivers).

PROCESS CAPABILITY
The 3rd edition of PPAP is much more specific about capability indices than the previous edition. In section I.2.2.9 it states that the capability, we are specifically told that

"The index for estimating process capability or performance will be agreed upon by the customer and supplier. Cpk and Ppk are described below. Other methods more appropriate for certain processes or products may be substituted with prior customer approval."

As with the MSA methods, we have interpreted this to mean that we must use the Cpk and Ppk as described in the PPAP & SPC manuals, or else get written customer approval for alternatives.