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February 2012

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From:
"Amol Kane (Asteelflash,US)" <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Amol Kane (Asteelflash,US)
Date:
Tue, 21 Feb 2012 06:34:08 -0800
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Richard, you can still use the central limit theorem for averages from the data population and do your analysis on the means instead of the individual values.

I would be curious to know if/how that works out

Regards,

Amol Kane | Process Engineer

AsteelFlash Group - US East
941 Route 38, Owego NY 13827
Phone: (607) 687-7669 Extn 349 | Website: www.asteelflash.com



-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Richard Kraszewski
Sent: Friday, February 17, 2012 3:22 PM
To: [log in to unmask]
Subject: Re: [TN] Correlation Factors for ROSE Testing & Cpk

Thanks to all who responded to this string. Realized it could strike a chord. 


To carry this a step further on a very related topic... 

Any of you guys ever try to run a Cpk on ROSE data sets?  Most of the times I've tried to over the years, the data sets have been non-normal, single tailed distributions, with highest counts near zero and then tailing off towards 10.06. (Similar to having only the right side half of a normal distribution curve).  They have defied data transformation to a normal distribution, hence can't really run a proper capability analysis (data of course must be normal for a Cpk).  

You could of course (at least within Minitab) try to run as a non-normal distribution and just report a PpK, however with such a high count near zero it's next to impossible to find a statistically supportable non-normal distribution. 

I would appreciate any related experiences and/or thoughts on this topic.  


Rich Kraszewski

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Richard Kraszewski
Sent: Thursday, February 16, 2012 2:00 PM
To: [log in to unmask]
Subject: [TN] Correlation Factors for ROSE Testing

While I realize that IPC specifically and the industry in general, does not support the use of ROSE correlation factors for the various testers, I have a need to see the official document that at one time quoted these specifically allowed factors.

I took a cursory look though all 230 pages of IPC TR 583 and didn't see that table. 

I seem to recall a military specification that had that table. Was it 454? 28809, 2000?

Does anyone recall?


Rich  Kraszewski / PLEXUS
 



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