Deming’s PDSA vs Lean PDCA

My LinkedIn reply to a post on Lean’s use of the Plan, Do Study, Act (PDCA) cycle.

Common Mistakes with the PDCA and also its History | .  Overview of the main causes of failures in a PDCA which will cause lean projects to fail. Also, the history…


For a history on the PDCA and comparison of the PDCA to the Deming-based PDSA, I recommend the following article:  Foundation and History of the PDSA Cycle

The PDCA was developed in 1950. Deming improved upon the concept in 1986 and replaced the PDCA with the Plan, Do, Study, Act (PDSA) cycle. “Deming never embraced the PDCA.”

The “So what?”  For advocates of Continuous Quality Improvement (CQI), we need a better strategy for leveraging the various methodologies and tools.

Deming is the only expert that correctly identified that reducing variation from the ideal is THE key to CQI.

Broader description of the variation principle

Employee Suggestions: Deming versus Lean

LinkedIn reply to a “re-post” of a 2007 post at on the topic of employee suggestions:

A Different “Lock Box” No, this isn’t about Al Gore and his infamous Social Security ‘lock box.’ This is about suggestion boxes that we sometimes see hanging on[..]

The contributions of W. Edwards Deming provides context for suggestions.  For instance, if you ask employees “What’s not perfect ?” , the suggestion box would always be overflowing.

The follow-up question is asking if the “imperfection” are recurring (common cause variation), or represent a temporary effect (special cause).  The majority of the imperfection will be common cause variation that requires a permanent change in the system.

Deming also accurately estimated that failure to understand variation resulted in a situation where 95% of change results in no improvement.

I’ve seen too many “lean” projects waste resources overreacting to a special cause and too many claiming success from changes that could not be sustained.  Assess your knowledge of variation at the following:

The fact that the topic was re-posted from 2007 indicates the need for application of a better methodology. Without a change in strategy, this post  can be re-posted in another 9 years.