Posted Under: Deming,Scientific Thinking,Statistical Thinking
As we saw on Part I, there are some fundamentally flawed conceptual problems with Six Sigma and its statistical underpinnings are shaky indeed.But the aspect of Six Sigma that makes it that makes it least useful as a tool to improve competitiveness is that it is based on defect detection and elimination (reduction) and not improvement.Removing the defects from a process does not improve it. It merely allows it to operate the way it was intended to operate. It is somewhat counterintuitive, but one cannot improve a process by reacting to its outcome.
That is what Deming is saying in the 3rd of his 14 points, “Cease dependence on inspection as a means to improve quality.”Of course removing defects is desirable. And if there are a lot of defects, rework, scrap, etc., eliminating it will be all to the good, but that doesn’t change the fundamental operation of the process. In order to do that, one must concentrate efforts on working upstream.
Over the years in consulting I have always differentiated between two types of variables. Those that are process outcomes; what the customer sees. I call these Key Quality Characteristics. Upstream are the variables that, in some combined and interactive way produce those results. I call these Fundamental Process Variables.For example, a key quality characteristic of a magnetic disk for a disk drive might be it’s flatness. In today’s demanding environment, recording disks must be extremely flat. The customer demands it. But disk flatness is a result of a machining process. In that sense it is an outcome.
To make a disk more flat it is necessary to understand the variables of the upstream process that govern flatness; the grinding pressure, the abrasive particle size of the grinding slurry, etc.Detecting disks that aren’t flat (defects) does not make disks flatter. To improve disk flatness requires action on the fundamental process variables.This seemingly semantic difference may seem trivial, but on the contrary, it drives improvement efforts and ultimately determines the level of competitiveness a company can attain.
Many companies execute well, but there’s more to competitiveness than that. Again we can look to Deming for the fundamental message. One of my favorite quotes of his is, “It’s all very simple, really, pay attention to quality in the right way, costs will go down and you enter the market with the best quality at the lowest cost. You will capture the market.” This is from an interview he gave to the New York Times many years ago. It is also from the message he brought to Japan in 1950. It is as true today as it was then, the difference being that today there is no doubt that it is true.Next is Part III – How the approach to improvement determines competitiveness.