ASQ Quality Progress, May 2019 article: In No Uncertain Terms

Key Point: “When thinking about the terms “continual” and “continuous,” you could easily argue that a relative difference exists, as evidenced by the terms’ various definitions in Table 1. The main difference between the terms is time—in the definitions of “continual,” there are breaks in time. In the definitions of “continuous,” however, there aren’t.”

W. Edwards Deming is recognized as developing the new philosophy for quality management. The distinction between continual and continuous identified above aligns with his philosophy. Deming concluded that if he was to reduce his message to just a few words, it all has to do with reducing variation.

At an individual level, improvement is continual.  At a group or system level, the improvement must be continuous because quality either gets better or it gets worse.

The article also references ASQs definition of CQI, as stated by authors Jeffrey K. Liker and James K. Franz that included the statement: “In reality, continuous improvement is a vision, a dream, and no company in real life can possibly always get better.”  I disagree with this contention. The statement as to the impossibility of improvement supports the need for a broader philosophical context that is provided in ASQ’s description of variation:  What is Variation? – The Law of Variation | ASQ

” … The Law of Variation is defined as the difference between an ideal and an actual situation. ..

An ideal situation represents a standard of perfection—or the highest standard of excellence defined by stakeholders, including direct customers, internal customers, suppliers, society, and shareholders. 

Though manufacturing groups and service providers strive for an ideal situation, they usually do not achieve this goal. Therefore, stakeholders almost always experience some variation from the perfect situations they envision. Reducing the variation stakeholders experience is the key to quality and continuous improvement.

A more common understanding of variation would provide a needed context for understanding the important distinction between continual and continuous.

In regards to travel, I commute to work via an automobile.  I want a transportation system that is safe, affordable, economical, does not harm the environment and is continuously being improved.

On an individual level, a continual improvement would include car maintenance and complying with traffic laws. Continuous improvement of the system (24×7, 365 days a year) requires the involvement of many people.