Plows vs Tractors

How to Teach Statistical Process Control (SPC)

Lately I've become concerned about how people learn statistical process control. Most trainers teach participants how to do all of the calculations manually and then show them how to do it using a tool like the QI Macros for Excel SPC Software.

I don't think people should have to learn how to do things manually. It's like teaching a farmer how to plow a field with a plowshare, when there's a brand new tractor that can plow eight rows at a time sitting right on the edge of the field. It's like teaching a person everything there is to know about the generation and distribution of electricity before you let them turn on a light bulb. It's a waste of time.

It used to be important to do it manually because you had to if you wanted to get results (which meant that few people ever did it.) Many people feel compelled to teach it that way, because that's how they were taught, but it no longer adds value from my point of view. It's just a way to fill up the class time. It's a way to turn a one-day class into a five-day class.

I'm biased about this because I spent five days in a control chart class doing calculations manually, but only spent two hours discussing what the charts are telling us, which is the only truly important part of the class. I came away knowing enough about the calculations to know they were too complex to do manually, and not knowing anything about reading the charts and using them.

Employees are too busy to waste time learning more than they need to know. We no longer have the luxury of learning everything there is to know before we do anything. We only have time for the essence.

The 4-50 Rule: 4% of the knowledge about any subject will give you half the benefit. The more you teach beyond this point, the more diffused, esoteric and seemingly complex the knowledge becomes. If you teach someone everything, they will have no idea what's important and what isn't. They know it all, but they know nothing. They have too many choices to take action effectively.

Here's my point: 
Let software do the hard work accurately which will free you up to do the important work of analyzing the charts and making improvements. Stop majoring in minor things. Juran said it well: "The vital few vs the trivial many." This applies to knowledge as well as improvements.

Once you've learned the essence, it's easy to add to that body of knowledge. When you've learned the whole body of knowledge in one shot, it's hard to decide which portion to use and when.

That's one of the reasons I developed Lean Six Sigma Demystified. You don't have to know everything to improve your business, just a few key concepts, methods, and tools. Eventually you'll acquire all the knowledge you need, but too much too soon is a recipe for failure.

Rights to reprint this article in company periodicals is freely given with the inclusion of the following tag line: "© 2008 Jay Arthur, the KnowWare® Man, (888) 468-1537,"

Free Lean Six Sigma Yellow Belt TrainingTake our FREE Lean Six Sigma Yellow Belt training online.