RE: Statistical Control and Purpose

[Myron Tribus <mtribus@home.com>]

Steve Prevette wrote:
>With respect to Dan's comments, I do find myself in a position somewhat
>contrary to Dr. Deming's, Shewhart's and Wheeler's predictions.  The issue
>is - does an "uncontrolled" process eventually gravitate towards stability
>and statistical control, or does it go chaotic?
>
>I can only answer with my personal observations with interventions into
>processes that appeared to have a low level of management control, purpose,
>or aim.  I found most of them had already achieved a state of statistical
>control.  The theory I have proposed to myself is that given a long time
>interval for things to settle out, and with processes that have a low level
>of external factors impinging upon them, a form of predicatibility settles
>in.

I suggest that if we examine systems in which there has been no 
effort to achieve statistical quality control, we will find one of 
two results:

1) The system is stable, producing goofs, flaws and errors at a 
fairly steady rate.  I found such a system where the CEO felt that if 
they did not produce about 1% defects, they were spending too much 
money.  (Hardware for very cheap luggage)

2) The system will be unstable as the management continues to tamper 
and try to improve things without any theory to guide them.  This can 
also happen if the outside conditions vary significantly.  For 
example, constantly changing suppliers looking for lowest cost.

Myron Tribus,  350 Britto Terrace,  Fremont, CA 94539
Ph:510 651 3641  Fax: 510 656 9875   e-mail: mtribus@home.com
There is no such thing as an immaculate perception.  What you see 
depends upon what you thought before you looked.
=======================================================================