Community Trekker

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Jan 11, 2014

## How to calculate Cpk?

In most of JMP reference books from sas , how to calculate Cpk? we are told that

1. If data are normal or similar to normal distribution, then go it from analysis>distribution> capability

2. If data are non normal distribution, in analysis>distribution, detect what its distribution is? then calculate Cpk corresponding to identified distribution, analysis>distribution>capability, and select its corresponding distribution from tab.

However, when I study the reference book, Quality and reliability methods JMP 10, where it demonstrates us how to calculate Cpk as follow

1.  analysis>quality and process>capability platform

2. add multiple measurements data into Y, column

3.  in goal plot and capability box plot, add normalized box plot,

4. get Cpk index

in my understanding, data normalization cannot change its origin data distribution, saying, its origin distribution is far away non normal distribution, after being normalized, the corresponding new data also is non normal distribution, is it right? if so, it is not apporpriate to calculate Cpk in this way.

1 ACCEPTED SOLUTION

Accepted Solutions

Super User

Joined:

Feb 10, 2013

Solution

## Re: How to calculate Cpk?

Mujahida,

Scott Wise from JMP gave a webcast a few months ago that covered Cpk calculations and Cpk for "non-normal" data. Specifically the second segment on non-parametric process capability may help answer your questions.

http://www.jmp.com/en_us/events/ondemand/mastering-jmp/analyzing-process-capability.html

Karen

Super User

Joined:

Feb 10, 2013

Solution

## Re: How to calculate Cpk?

Mujahida,

Scott Wise from JMP gave a webcast a few months ago that covered Cpk calculations and Cpk for "non-normal" data. Specifically the second segment on non-parametric process capability may help answer your questions.

http://www.jmp.com/en_us/events/ondemand/mastering-jmp/analyzing-process-capability.html

Karen