Question: A Lower Limit Below Zero?
Question from a reader: As we know sometimes when we calculate the Natural Process Limits, the Lower Limit is negative. In some measures, that’s not
Blog: Reader Questions
Question: Is it Appropriate to Plot Averages on a Process Behavior Chart?
I’ve gotten this question a few times recently, basically asking if it’s OK to plot metrics like these on a Process Behavior Chart (PBC): Weekly
Question: Why Are There Different Ways of Expressing the Formulas for the Limits?
Here’s a good question from a reader: In your KaiNexus webinar on PBCs you use: LCL = Mean – 3*(MR bar)/1.128 and UCL = Mean
Question: Why are the Limits so Wide?
A reader shared a Process Behavior Chart with me and asked this: “On the Falls_Harm tab, the limits seem a bit far away from the
Question: Why are There so Many Data Points Outside of the Limits?
I got a message from a reader of my book Measures of Success: React Less, Lead Better, Improve More. The questions were: “I entered data from
Question: How Can I Add More Data Points to a Process Behavior Chart?
A question that a few people have asked: “Your PBC template, by default, only shows 25 data points. How can I add more points to
Question: Why not use Other Types of Control Charts?
A reader from Hong Kong asks a question that has been asked by others: “There are many types of control charts under the six sigma
Question: When do we Recalculate the Limits in Process Behavior Charts?
A reader asked: “I am wondering at what point do you recommend recalculating the average and upper and lower limits?” Generally, we’d recalculate limits when
Question: Do the data have to be normally distributed for Process Behavior Charts to be valid?
A reader asked: “Do the data have to be normally distributed to use a Process Behavior Chart?” The short answer is “no.” Process Behavior Charts,
Question: Why is there a Scaling Factor for the Upper and Lower Natural Process Limits?
A reader question: “Mark, Thanks to your help, and some push from an IHI conference there is some pull in our organization for Process Behavior
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Hi. I'm Mark Graban
I help businesses leaders and workers improve their activities and processes. With methods grounded in Lean, math and science — backed by data. Better to make choices based on facts — instead of opinions, hunches, or feelings. Learn how to convert data, metrics, and charts into knowledge and wisdom — to drive more improvement. That’s what I do and why I wrote "Measures of Success."
