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Level III

## Cauchy distribution. Where is Process capability button?

Why where is no Process Capability button? Or you can't do it with Cauchy's distribution data.

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Super User

## Re: Cauchy distribution. Where is Process capability button?

According to the JMP Documentation, the Cauchy distribution has an undefined Mean and Standard Deviation. Based upon that, I assume JMP does not have Cp and Cpk for that distribution and thus no need for the button.
Jim
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Level III

## Re: Cauchy distribution. Where is Process capability button?

Sorry... Why is there no process capability button?

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Super User

## Re: Cauchy distribution. Where is Process capability button?

According to the JMP Documentation, the Cauchy distribution has an undefined Mean and Standard Deviation. Based upon that, I assume JMP does not have Cp and Cpk for that distribution and thus no need for the button.
Jim
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Level III

## Re: Cauchy distribution. Where is Process capability button?

Yes, but then how do I calculate PPK? Should I take the nearest distribution, if it is? Or should I calculate PPK using Standard Deviation? I need to evaluate the process with nonnormal data distribution.
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Super User

## Re: Cauchy distribution. Where is Process capability button?

Have you tried fitting all the Distributions, and then determine which have a significant Goodness Of Fit?  You could then use that distribution for your Cp and Cpk

Jim
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Level III

## Re: Cauchy distribution. Where is Process capability button?

yes I click Fit all

And recieve only three, where Cauchy has a priority.

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Super User

## Re: Cauchy distribution. Where is Process capability button?

Check out the other fits.....they might give you good estimates
Jim
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Level III

## Re: Cauchy distribution. Where is Process capability button?

but goodness of fit points to Cauchy

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Staff

## Re: Cauchy distribution. Where is Process capability button?

Actually, the mean of the Cauchy distribution is defined but not the higher moments. So, no variance, no standard deviation. No standard deviation, no Ppk.

Learn it once, use it forever!
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Level VI

## Re: Cauchy distribution. Where is Process capability button?

And, just as an aside, if you're responsible for improving a process that outputs data that are really Cauchy distributed, you might want to update your resume...

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