How to Create a Custom Control Chart for Irregular Time Intervals in JMP?

[#1]

Hi Everyone,

I'm working with process data recorded at irregular time intervals and want to build a custom control chart in JMP that accounts for these variations. What’s the best approach or tool within JMP to handle this? Are there scripts or examples available for reference?

Thanks and Regards

Namrata Hinduja Geneva, Switzerland

[#2 · Accepted solution]

Something I learned this week that may be of help:

Create your chart using Control Chart Builder > red triangle > uncheck Show Excluded Region, Include Missing Categories, and Test Excluded Subgroups. That may give you a neater Control Chart.

[#3]

First, welcome to the community.

Regarding control chart method (Shewhart), I'm not sure if you understand the questions that are being answered with the charts.  There are 2 specific questions the charts answer:

1. Is the within subgroup variation, due to the factors changing within subgroup, consistent and stable?  If you change what factors are changing within subgroup over the time series because you are varying the time interval, you cannot answer this question.

2. Is the variation between subgroup, due to the factors changing between subgroup, more than that predicted by the within subgroup variation?  If you change what factors are changing within and between due to varying the time between sample, you cannot answer this question.

So even if you could create such a chart, it does not satisfy the purpose of the methodology.

You can, of course, plot the data however you want, but not as control charts per se.

[#4]

Thankyou Sir