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Capability calculations for True Position

VinniUSMC
Has anyone come across this as a means of calculating Cpk of a true position?

http://documentation.statsoft.com/ST...tionCapability

I think it should be possible, but I'm not sure if this is the answer or not. I was thinking about how something along the lines of the complex plane (or vectors/trig) could be used to identify grouping of a positional tolerance based on its quadrant within a unit circle, and then could be used to calculate Cpk. It's not unheard of. The normal distribution of a multivariate system is calculable, so why wouldn't a statistic that is related to the normal distribution in 1 variable work for higher dimensions?

I'm thinking that there must be a way to calculate the variance of position based on the the quadrant it falls in. Whether it's a trigonometric function, or a complex function.

Anyone have any input as I dive into this blackhole?

Curiosity killed the cat, hopefully I'm not a cat.

Parents
  • As I understand the Volvo doc, here is my "translation" :
    test CPK vb.zip

    Don't forget that I work essentialy on prototypes, so I'm not user of those tools Disappointed.
  • in reply to JEFMAN
    Which macro? I'm playing around with the file from this post, and all of the calculations seems to work. Some of them are a bit above my head, so I'm trying to work through exactly what is happening in each call, but it's working great from what I can tell.

    My only question would be on the final calculations, there are just numbers in those cells, so there's no indication of what is being calculated for Cp/Cpk1/Cpk2. I think that the calculation is not the standard Cpk calculation, so I'm not sure how to double check those. I like the addition of the line chart that changes with the change in angle. Very professional. Slight smile

    Kudos to you for doing this on a Sunday morning too. Super Jefman to the rescue.
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  • in reply to JEFMAN
    Which macro? I'm playing around with the file from this post, and all of the calculations seems to work. Some of them are a bit above my head, so I'm trying to work through exactly what is happening in each call, but it's working great from what I can tell.

    My only question would be on the final calculations, there are just numbers in those cells, so there's no indication of what is being calculated for Cp/Cpk1/Cpk2. I think that the calculation is not the standard Cpk calculation, so I'm not sure how to double check those. I like the addition of the line chart that changes with the change in angle. Very professional. Slight smile

    Kudos to you for doing this on a Sunday morning too. Super Jefman to the rescue.
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