topic Re: Capability Indices calculation for Nonnormal Distributions in Percentile Methods in Discussions

Capability Indices calculation for Nonnormal Distributions in Percentile Methods

Luna — Fri, 09 Jun 2023 00:43:05 GMT

Hi, I would like to figure out how JMP 16 Calculate Ppk in non-parametric method. So I calculate Ppk in R code with the formula in online documentations, but the results are very different. Could anyone help me to understand if it is my calculation error or the documentation?

Re: Capability Indices calculation for Nonnormal Distributions in Percentile Methods

Luna — Mon, 13 Dec 2021 01:20:49 GMT

Sorry I post wrong JMP results, the JMP results are as follow:

Re: Capability Indices calculation for Nonnormal Distributions in Percentile Methods

frank_wang — Mon, 13 Dec 2021 02:57:35 GMT

Hi Luna

JMP基础统计的结果有吗？看看分位数的结果是否一致。如果公式本身没有问题的情况下。

Re: Capability Indices calculation for Nonnormal Distributions in Percentile Methods

Luna — Mon, 13 Dec 2021 03:39:38 GMT

你好，我简单用R计算了一部分百分位数，和JMP略有差异，但Ppk计算结果差别太大了（R:2.026, JMP: 1.678），可能不是百分位数计算方法造成的误差.

Re: Capability Indices calculation for Nonnormal Distributions in Percentile Methods

worldwyn — Mon, 13 Dec 2021 19:58:13 GMT

For those having trouble following the conversation...

Are there any results for basic statistics? See if the results of the quantiles are consistent. If the formula itself is not a problem.

Re: Capability Indices calculation for Nonnormal Distributions in Percentile Methods

worldwyn — Mon, 13 Dec 2021 19:58:54 GMT

For those having trouble following the conversation...

Hello, I simply used R to calculate some percentiles, which are slightly different from JMP, but the Ppk calculation result is too different (R:2.026, JMP: 1.678), which may not be the error caused by the percentile calculation method .

Re: Capability Indices calculation for Nonnormal Distributions in Percentile Methods

frank_wang — Mon, 13 Dec 2021 23:55:42 GMT

Hi Luna

考虑到基础统计量计算结果的不同导致最终结果的不同。不知道是否方便讲JMP中基础统计模块的0.99865/0.00135的结果显示一下。方便和R做对比。

具体的方法可在红色三角形中选择option-->客户定制。

Re: Capability Indices calculation for Nonnormal Distributions in Percentile Methods

Luna — Thu, 16 Dec 2021 05:29:53 GMT

Hi Wang,

Sorry for reply so late, I calculate the P0.99865 and P0.00135, the result from JMP and R are still very close.