Diane asks:
>I have a Deming related question to raise, I hope this is a good place for
>it.
>
>I need some help understanding "special causes" as W. Edwards Deming would
>define them. I can't quite find what I'm looking for in the books I have
>at home. I am in the process of defining something I believe to be an
>opportunity for improvement. However, I struggle with the question of
>whether my idea would be considered "tampering". Also, it was suggested
>to me that the issue I raise is a "special cause". Is it desireable to
>eliminate special causes before we work on common causes? I would much
>rather be tossing my thoughts around with my peers and my management.
>However, the issue I discuss here is an undiscussable, at least among my
>co-workers.
Then she went on to describe a pretty complicated system that is at work
in her company.
The first thing that comes to my mind in reading this is that problems or
variation in outputs you are encountering reflect the capabilities of the
system. I'm not sure, but it doesn't seem like we are dealing with
special causes here. I suspect the problems are inherent in the way your
system now operates, and dealing with them one on one will not help you
improve the system. Perhaps you already know this. A good and very
accessible book that talks a lot about such ideas is Brian L. Joiner,
Fourth Generation Management: The Business Consciousness, published by
McGraw-Hill, 1994. It explains the ideas of common cause and special
cause variation clearly and gives lots of examples of tampering and how to
use control charts to improve organizational system performance.
-- Good luck, John Woods jwoods@execpc.com