TQM = continuous process improvement

Process improvement requires that processes be stable, or under statistical control

Statistical control - a state of random variation; it is stable since the limits of variation are predictable

Once the process has been stabilized, special causes of variation can be dealt with

Once special causes of variation have been removed, process improvement can begin

Processes are improved by addressing common causes

To be able to distinguish between special and common causes of variation, we must let the system run for a long time and measure continuously its output

Tampering with a process - ascribing a variation, or a mistake, to a special cause when in fact the cause belongs to the system. This overadjustment adds variation to the process.

Ascribing a variation, or a mistake, to the process when in fact the cause is special leads to doing nothing.

Acceptable Defects: Rather than waste efforts on zero-defect goals, Dr. Deming stressed the importance of establishing a level of variation, or anomalies, acceptable to the recipient (or customer) in the next phase of a process. Oftentimes, some defects are quite acceptable, and efforts to remove all defects would be an excessive waste of time and money.

TAMPERING VS. IMPROVEMENT

Tampering means making harmful changes in reaction to chance events (i.e., common causes of variation).

Tampering means adding additional variation by unnecessary adjustments made in an attempt to compensate for common cause variation.

Tampering is not improvement.

Improvement of a stable process requires fundamental change in the process

Improvement means reducing a process's variation and establishing an acceptable process average