Hello

I have just read this article on the Minitab blog regarding the 3 options in Minitab for excluding data points from control limit calculations. I tried to post the hyperlink, but the forum rules does not allow me to post the link until I make 10 posts. If you google "Leaving Out-of-control Points Out of Control Chart Calculations Looks Hard, but It Isn't" by Cody Steele | 01 June, 2017, you can access the Minitab blog article. Leaving Out-of-control Points Out of Control Chart Calculations Looks Hard, but It Isn't

My question: Why is the upper control limit different in option 1 when compared to options 2 and 3?

I would have expected the mean and control limits to remain the same irrespective of how you exclude the data points in the calculation. It is getting difficult to explain to my manager and client why these small differences are acceptable.

Thanks

Alakazam

I have just read this article on the Minitab blog regarding the 3 options in Minitab for excluding data points from control limit calculations. I tried to post the hyperlink, but the forum rules does not allow me to post the link until I make 10 posts. If you google "Leaving Out-of-control Points Out of Control Chart Calculations Looks Hard, but It Isn't" by Cody Steele | 01 June, 2017, you can access the Minitab blog article. Leaving Out-of-control Points Out of Control Chart Calculations Looks Hard, but It Isn't

My question: Why is the upper control limit different in option 1 when compared to options 2 and 3?

I would have expected the mean and control limits to remain the same irrespective of how you exclude the data points in the calculation. It is getting difficult to explain to my manager and client why these small differences are acceptable.

Thanks

Alakazam

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