by Ted Eytan, on 07 Sep 2007 11:12 am
The Journey
Under Control, but Capable?
This week I have been invited to participate in a consultant training that Lee and our Sensei are conducting in our Health Plan Division. Many here are not doing this for the first time. There’s a lot of new things for me, as well. Besides the learning that I am engaging in myself, it’s great to see colleagues from another division go through the process, as they apply what they are learning to what they do for members. We are all connected.
We prepared a control chart as part of an exercise today, the first time I have done this. To create this chart, a group of 5 of us was responsible for hammering a nail into a board to a specific depth, drawing the histogram (pictured), and calculating the process capability. Ours had a bit of an uneven distribution. Can you tell why? (Hint, there were 5 people on the team)
Our sensei walked by and said, “It looks like there is good process control, but not capability.”
As usual, I see many correlations to what we can do in clinical medicine….
on 10 Sep 2007 at 5:47 pm 1.Mark Graban said …
I’m either nitpicking or confused… that looks more like a histogram than a control chart, pictured.
on 10 Sep 2007 at 5:49 pm 2.Mark Graban said …
Ah, let me withdraw that comment… I was confused. You said that was the histogram.
It looks like each individual was capable, but the “process” overall was not capable, correct?
on 10 Sep 2007 at 9:58 pm 3.Ted Eytan said …
Hey Mark,
Yes..almost. The key is that there were 5 of us hammering nails, and that’s why there appear to be multiple distributions on the histogram.
You could say that most of us had “control” because we have narrow standards of deviation. It looks like one person may have had good “control” and was “capable” (the customer’s tolerance relative to the sig sigma of that person was high), but overall, the process is not capable because it has a wide six sigma relative to the customer’s expectations, because of the variability of individuals on the team.
I took this and asked, “Suppose there are 5 family physicians in a medical center, and each of them practices uniformly according to what they learned in medical school, yet each of them learned a different way. Do they have good control? Yes. Is their care process as a team capable? Maybe not….”
on 12 Sep 2007 at 5:54 am 4.Pete Abilla said …
Not quite: A control chart is simply a picture of how a process is performing — wholly devoid of any value-judgments: it’s just the facts.
Capability, on the other hand, is a question about whether or not the performance of a process is meeting the requirements of the customer. Capability, is typically a range (x to y) or, in some companies, is actually an arbitrary number (must serve customer within blah, blah, blah).
The Taguchi Curve teaches us that if there is a slight deviation of the mean either to the left or right of what he calls “target”, then cost jump exponentially. Imagine producing tire with a required thickness — if it’s too thick or too thin, the costs are very high in warantee claims or death.
What is missing in your picture is…capability, which can be shown as a C (which is a point estimate) or Cpk, which is a range (capability index).
All that is shown in the picture is really the facts.
on 12 Sep 2007 at 6:03 am 5.Ted Eytan said …
Pete,
Excellent addition/correction and good information for an amateur like me. Continuous improvement of the posts on this blog is most welcome!
on 12 Sep 2007 at 6:29 am 6.Pete Abilla said …
Ted,
We’re all amateurs — learning as we go. Keep up the great work. DailyKaizen is honest and free of pre-tense. I love it.
on 14 Sep 2007 at 6:22 am 7.Curious Cat Management Improvement Blog » Management Improvement Carnival #19 said …
[...] Under Control, but Capable? by Ted Eytan - “We prepared a control chart as part of an exercise today, the first time I have done this… As usual, I see many correlations to what we can do in clinical medicine…” [...]