The Truth About Data and PDSA/PDCA from a Toyota Publication
Out there in the Lean and quality improvement communities, you sometimes hear some silly things. Sometimes, I want to attach the “Lean As Mistakenly Explained” (or L.A.M.E.) label to what’s said when it really seems off the mark from what Lean is really all about. Davis Balestracci, a columnist for Quality Digest, passed along something he heard from a “Lean guru” (whatever that means):
“In my opinion, any approach should also involve the use of data in some way, shape, or form. I once had a lean sensei (local “guru”?) vehemently make the point that lean does not involve data at all.”
What?? Read his entire column here. I asked Davis, in a comment, if he had misunderstood the speaker. I was trying to give the speaker the benefit of the doubt, given the oft-repeated quote from Toyota’s Taiichi Ohno:
“Data is, of course, important in manufacturing,” Ohno often remarked, “but I place greatest emphasis on facts.”
Ohno wasn’t saying to ignore data. He was saying to not rely on reports – today, that would be spreadsheets and “dashboards.” Reports and data can be skewed (intentionally or inadvertantly). Ohno was saying we have to go to the Gemba (get out of the office) and see what can be verified with our own eyes. I’ve never heard anybody say that data isn’t important in Lean.
I *have* heard Six Sigma people say, incorrectly, that Lean is just qualitative and Six Sigma is the only “data-driven” methodology. That’s false.
I was taught to use data in Lean improvement work and that’s certainly the message sent by Toyota – to use data (and statistics!) when appropriate and helpful. Not everything can be quantified (a key Deming principle), but we certainly look for data and measures where we can, rather than relying on feelings and opinions. Did patient satisfaction improve? “I feel like it did.”
Wait – how do we know that it improved? Do we have data that back up that claim? I recently found a Toyota publication that was (probably somewhat sketchily) shared on a Chinese website. It says, in part (drawing on Masaaki Imai and his book KAIZEN, which is cited in footnotes): The principles of Kaizen are:
- the most important company assets are the people
- evolution of processes will occur by gradual improvement rather than radical changes
- beneficial changes are to be implemented immediately where possible
- improvement recommendations must be based on statistical and quantitative evaluation of processes
I don’t know who is running around saying “data doesn’t matter” in Lean (unless it’s, like I might suspect, a “Lean Sigma” person who learned some sort of claptrap about Lean not being “data-driven,” instead of somebody who has learned directly from Toyota and its people). You can’t fault individuals if they’ve been taught badly (even if that person is a professor). Related post from 2013: Can’t Always Believe Somebody Saying “Toyota Would Tell You To…“ Does Toyota think data should be involved? More evidence, from the document:
“The Check is the measurement of the Do. This means that the countermeasures implemented must be measurable. If they are not, there has been a failure in the planning section. As is understood, if you can not measure it, it is not worth doing.”
Here is a point where Toyota strays from what Dr. Deming taught them about things being measurable:
“… the most important figures that one needs for management are unknown or unknowable (Lloyd S. Nelson, director of statistical methods for the Nashua corporation), but successful management must nevertheless take account of them.”
That’s an interesting divergence of thought. those two equally valid opinions or a difference between right and wrong? Is it possible to prove or disprove either statement (“if you can not measure it…” or “the most important figures… are unknown or unknowable…”)? Seems like two different opinions. I’d align myself with Dr. Deming, based on my own experiences.
Does “Plan Do Study Adjust” Jump to Solutions?
I also hear some loud voices that say PDSA (Plan – Do – Study – Adjust) is a flawed model because it supposedly starts with the “Plan” to implement a certain solution. That is, of course, hogwash and you realize it as such if you’ve been taught or mentored on PDSA/PDCA from a Toyota person.I’ve been lucky to have that sort of coaching. And, that information is available in books, too.
“Plan” actually begins with studying and understanding your system and the problem. We have to, in “Plan” properly define a problem so we can then understand causes and root causes… long before every thinking about countermeasures to test in the “Do” phase of PDSA. Here’s a diagram from that same Toyota publication:
What is “Plan,” according to Toyota? Define the problem, analyze the problem, identify causes, AND plan countermeasures. There is no “jumping to solutions” in this approach. You see the same thing in the Toyota “8-step problem solving model” and its mapping to PDSA (and its mapping to the Six Sigma DMAIC model) from the “Kaizen Factory” website. So, if you ever hear these statements:
- Lean is not about data
- Lean would say “kick the patient out of the room because their time is up“)
- PDSA says jump to a solution without first studying the problem
I think you can definitively say, “WRONG!”
Sometimes, we have different opinions… and that’s OK. Sometimes, things are factually incorrect.