Lean Six Sigma and Deming’s 14 points (pt3)

The third point is easier to understand but is ignored by most because it is considered too ideal. Deming’s third point is “Cease dependence on inspection to achieve quality. Eliminate the need for inspection on a mass basis by building quality into the product in the first place.”

It should not be read that inspection is necessarily bad, but that the dependence on final inspection to drive quality is wrong. Many people tell me that building quality in the product so as to avoid a need for inspection is impossible. Is that true, it might be but at a lot less occurrence rate than you expect.

I read this one to say that you manage the product quality through managing the process capability, not the part quality by inspection. The difference is that we inspect parts in order to estimate the process capability (percent non-compliant). Does Lean Six Sigma support this point by Deming?

If you have been taught by a good training provider, you should be answering yes. You are taught to work with continuous data rather than pass/fail data. The training should have focused on discussing % out of tolerance based on the inference of the population distribution not the sample that was selected. The low end trainers avoid this issue by teaching folks to use non-parametric statistical methods and defect counting as valid decision tools. Generally they also teach the Shewhart control charting methods rather than the Deming Control charting methods.

Deming’s view of common and special causes from control charts is a key difference in the good to not-so-good lean six sigma training. Shewhart charting (x-bar-r,…. and p-charts, …) methods generally identify every mid to high level stable business and stable manufacturing process to be out-of-control. The Deming charting methods more appropriately manage process data that is impacted by multiple previous processes and different material batches.

The Integrated Enterprise Excellence (IEE) methods do force you to manage to the process indicators not the product quality. When you build the linkages of part performance to the business performance you have a clear linkage to maintaining process capability within specified limits and the product will always be acceptable. This can be done with a properly developed value chain and e-DMAIC process.

Result – IEE supports Deming point 3 while standard lean six sigma may not.

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