PDCA …PDSA, Is it as Simple as a C or an S?


by Dan Strongin

There’s an old joke, about a venerated Catholic priest, who after many years of faithful service to the church dedicated himself to a full understanding of ancient Aramaic script. His work was so exemplary, that on his 90th birthday he was called by the Pope to the Vatican. It seems, they had found, deep in the bowels of the Vatican archives, a previously unnoticed version of the Bible that had been written hundreds of years before the more modern translations.

The priest arrived at the Vatican, his heart filled with piety, after a lifetime of celibacy and dedication to the teachings of the church. With great pomp and circumstance, the pope himself led the priest deep into the bowels of the Vatican, to a recently unearthed room, where a special table had been set up for the priest to do his work.

Weeks passed. Nothing was seen or heard of from the priest, except by those who brought him his food and drink and emptied his chamber pot. Then one night, after midnight, the Pope was awoken from his sleep by the most soul shattering scream he had heard in his life. Leaping to his feet, barely able to place his robe on his body, he rushed in the direction of the cries, following them down into the depths of the Vatican, until he came to the small room that housed the priest. There the old priest stood with his clothes disheveled, tears streaming out of his eyes, as he screamed at the top of his lungs “no, no, no!  We translated it wrong, it says celebrate, not celibate.”

Words have different shades of meaning. Different shades can lead to very different interpretations and thereby, different results, especially over time. In his later years, Dr. Deming changed the original acronym he called the Shewhart cycle, and everyone else calls the Deming Cycle or the Deming/Shewhart cycle by switching out the C for an S. Why did Dr. Deming change his mind, it can’t be arbitrary? Even a superficial reading of his work shows he was careful in his choice of words, both in what he said and the way he said it. But, in spite of his making the change, most quality practitioners, from ISO to Six Sigma, continue to use PDCA. Like the difference that would have been between celebrate and celibate, what have been the side effects of this seemingly simple choice?

According to the Oxford dictionary the definition of the word check is:
“…examine (something) in order to determine its accuracy, quality, or condition, or to detect the presence of something…”

and the definition of the word study is
“…a detailed investigation and analysis of a subject or situation.”

There is a world of difference between checking and studying. Does it follow that the current longstanding misunderstanding of the full intent of PDSA can be traced to the difference between checking and study? Can it be that simple? In one, checking, you look to determine accuracy or to detect the presence of something to blame, something that can be fixed. Finding fault, defects, finding something to blame, feeling in control, ranking and setting goals are the hobgoblins of modern management and the modern quality movement. When you combine the choice of the word check with an addiction to short-term profit, particularly in publicly traded companies, then throw in a pinch or two of the misguided religion of cost control fed by the simple minded saying “watch the costs and the profits will take care of themselves,” attributed to Andrew Carnegie, you will inevitably end up in the difficult state of affairs we find ourselves in. (Carnegie also said the importance of quality in an organization cannot be overestimated. Too bad people didn’t seize on that one instead.)

Psychologists have a term, folie à deux, which is when two people who may never have had a psychotic episode meet each other by chance, and something in each of them ignites a combined psychosis. If they had never met, they may never have had a problem. Is the original choice of C in PDCA in concert with the disease of short term thinking a folie à deux?

A singleminded focus on lowering costs through process improvement is a slippery slope on which you lose the opportunity to learn. The essential question is, plan, do and study what? And what do you then act on? You have to have a theory, to put those questions in context. Without context, nothing can be learned: it is the “science” of the foregone conclusion, not the scientific method.

The primary purpose of PDSA should be learning, ie.- understanding through experience. It is about constructing Knowledge, not just decreasing the range of variation around an average in a process that may, or may not have any bearing on the long term success of an organization. How do you even know if, like Nero, you will only be fiddling while Rome burns? Eight track tapes were far superior in sound quality to mini-cassettes. Eight track makers had great processes. But cassette players wiped eight track tapes off the face of the earth. Why?

You need so much more to survive in business than just good process. You need a way to be able to reasonably predict the future. And you need a way to prioritize how you use always limited resources within the context of what the market needs and what you can supply. You need Knowledge.  Learning married to experience leads to understanding. Understanding leads to better theories. Better theories lead to deeper knowledge.

In Henry Neaves Book, The Deming Dimension, he includes the following hand drawn version of the Shewhart Cycle, in Dr. Deming’s own hand. Notice the words “a test” and “small scale” and “what did we learn.”

PDSA is not mere error proofing.  PDSA is not project planning. PDSA cannot be removed from an appreciation for a system, nor from the psychology of the way the people will react to what you are doing and how you go about doing it. You have to optimize the whole and take people into account. It can be little more than a parlor trick if not seen through all lenses of the System of Profound Knowledge.

Years ago, I worked at the Ritz Carlton in Boston. I was the Night Chef in the Cafe at that time. The waiters, most of whom were originally from Italy and the Azores, used to brag how much money they made the day before at the race track. “I was up 800 dollars at one point!”  they would brag. I used to ask how much money they had at the end of the day. The answer was alway nothing, or worse. Much of what has been paraded as “savings,” by those who worship at the altar of zero defects, stayed on their spreadsheets, and never materialized in the bank. “A dollar of real money is worth more than a thousand in talk” (Maltese Falcon) Those who continue to use C rather than capital S are robbing themselves of an opportunity to learn, grow, and profit, with real money.

“Never-ending Improvement through Profound Knowledge”