Reader Questions Archives - Measures of Success

PBCs with Time Measures?

Question from a reader: For the Process Behavior Chart template, have you ever converted it to time? I was trying to map some lap times from my swim but it doesn’t seem to like time (I’m trying to measure consistency from lap to lap). My …

Question on Setting Limits

A reader writes: “I got this email from QI Macros for Excel, which I installed on my home computer a while ago. I find this story interesting as had never heard this: users in the healthcare field are advised to wait until their process has …

Question: Am I Recalculating the Lower and Upper Limits Correctly?

Reader question: “When you are recalculating the average because you see a shift, does the average from your previous calculation only take into account those values up to the new average? (not sure if this makes sense so I will ramble on a little bit …

Question: Why Use 25 Data Points for the Average & Limits in the Process Behavior Charts Template?

A question: I have a question about the formulas for columns C & E in your template. Is there a reason they’re set to only calculate the average on the first 25 data points as opposed to all them? My answer: Thanks for your question. …

Question: Does the System Need to be “In Control” to Get Started With Process Behavior Charts?

A question: Hi Mark — long time reader, first time sending a question…. I love your recent emphasis on eliminating “red/green” analyses, and moving toward more statistically sound tools like control charts. I’ve seen your slides and webinars on creating them. But one question has …

Question: Do I Need Normally Distributed Data to Use a Process Behavior Chart?

Question: To have a valid control chart (or “Process Behavior Chart”), don’t I need data that’s normally distributed? In other words, a “bell curve”? Short Answer: No No, your data doesn’t have to fit a normal distribution or any distribution. The PBC methodology is robust …

Question: Can the Lower Limit Below Zero (Negative)?

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 a practical value, like in the example below (where we set the limit to zero). Therefore we made the Lower …

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 average emergency patient waiting time Monthly average lost sick days Daily median waiting time for clinic patients The concern gets …

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 + 3*(MR bar)/1.128 When 3.0/1.128~=2.66 I use: Ave(x) +/- (2.66 × Ave(mR)) Those are just different ways of expressing the …

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 mean.” As I wrote back, the Lower and Upper Natural Process Limits are calculated based on the amount of point-to-point …