The Role and Purpose of Control Systems

At PPI (see Chapter 3) the measurement system and the employee reward systems were based on units produced, just as they were at Signetics. And that directly related to PPFs over 14 percent defect rate. It generated what it measured, and so its solution was to add control systems, such as Statistical Process Control (SPC), which, in and of itself, is a very good system when applied as a performance enhancement tool used to measure process performance as it happens. But as a control system, which was after the fact, it had no effect on quality output. All it did was confirm that indeed the defect rate was over 14 percent. It identified a varying number of areas where errors occurred, but it did little to aid in identifying solutions. 

Inappropriately applied control systems are the enemy of an efficient supply chain environment. 

Increase the opportunities for failure since there are now more steps in the 

Misdirect employees on what is important in achieving overall goals. Waste resources (time, floor space, etc.). 

And most importantly, move the error to somewhere else in the process rather than fix or eliminate the error. 

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