I feel very strongly about the value of Deming’s ideas. I am glad people challenge those ideas and try to push forward management thinking. Helping us manage organizations better (to get better results and allow people to better enjoy their jobs and lives) is why I value Deming’s ideas. To the extent we find better ideas I am very happy. I understand I will disagree with others on the best ways to manage, and believe healthy debate can be productive.
What Don Reinertsen discusses in the video, about special and common cause is not the best way to look at those ideas, in my opinion (though I would imagine it is the most common view). For data points that are common cause (within the control limits and not a special cause pattern) it is most effective to use common cause tools/thinking to improve. For indications of special cause (points outside the control limits or patterns in the data, such as continually increasing results that indicate a special cause) it is most effective to use special cause tools to improve.
This does not mean that a point outside the control limits is caused by a special cause (also know as assignable cause). It is just best to use special cause tools and thinking to address those data points (and the reason this is true is because it is most likely there is an assignable cause). The control limits do not define the nature of the point, they define the type of improvement strategy that should be used.
Don also says repeatedly that you don’t “respond to random variation” in Deming’s view. That is accurate. But then he implies this means you don’t address system performance, which is not. You work on improving systems (that are in control) by improving the system, not by responding to individual common cause data points (random variation) as if it were assignable cause variation.
The purpose of the control chart (that Shewhart developed) was to help you most effectively take action (knowing if special cause thinking, or system improvement, was the best improvement strategy). The control chart shows if the results are in control and tells you that the system is preforming consistently (and identifies a special cause so special cause tools can be used immediately, this is important because special cause improvement strategies are time sensitive). It tells you nothing about if the results are acceptable.
Continual improvement was also central to Deming’s management philosophy (based on the business value of the many improvement options available in every organization). For Deming this meant working on improving the system, if the results are in control, instead of trying to deal with finding a specific assignable cause for one data point and acting on that. If the issue is one of the system performance (no indication it is a special cause) the most effective strategy to get better results is to improve the system, rather than approach it as a special cause issue (examining individual data points, to find special items in that event to be improved). You can use special cause thinking, even where system improvement thinking would be better. It will work. It is just not very effective (improvement will be much slower) compared to focusing on system improvement.
I agree with Don that the United States mentality, not only in nuclear plants but everywhere, is to apply special cause thinking as the strategy for process improvement. This is one the areas Deming was trying to change. Deming, and I, think that setting your improvement strategy based on a common cause (system improvement) or assignable/special cause (learn what is special about that one instance) is the most effective way to achieve the best results. We believe in continual improvement. We believe that the effective way to improve, when a system is in statistical control, is by focusing on the whole systems (all the data) not assignable cause (special cause) thinking where you look at what is special about that bad (or good) individual result.
The economic consideration of whether the costs of improvements are worth the benefit is sensible (and I do not see Dr. Deming arguing against that). That is separate from the best method to improve. For Deming the best method to improve means using special cause thinking for assignable cause issues and common cause thinking for systems issues.
The idea of where to focus improvement efforts is not something Dr. Deming made as clear as he could have, in my opinion. So I see the argument of Deming not prioritizing where improvement should occur voiced occasionally. This is a weakness in Deming’s content, I believe, more than his philosophy (but I can understand it causing some confusion).