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 Variance Management On the Japanese Production Floors

Deming distained the idea of fully automated factories, where "robots painted robots".  He insisted that workers should not be regarded as machines, even though they were as essential to production as the machines.  He recommended a change in management attitude that where machines were seen as sources of errors and variances of various kinds that the workers should be trained to recognize and control.  Management managed people, while people managed machines. 

Managing the machines actually proved to be the easiest thing to do: Walter Shewart had done a lot of work in statistical analysis that showed that variances in machines were a mixed lot: some were controllable, and some were random.  He developed state charts, which were methods of interpreting plotted and tracked variances to determine, as the workers adjusted the machine, which errors were within their "sphere of control" and which were purely random.  Deming advocated an acceptance of variances that were random (and explicit allowances for those errors in product designs), while stating that management had a right to demand of workers an attitude of zero tolerance for controllable variances using the state charts of Walter Shewart to implement it.  This was embraced by the Japanese, because the state charts could be produced as proof of what was controllable and what was not.

But the state charts did more: With careful notation and training, a worker could adjust the machine, measure the results in the product, plot the results, and create statistical charts that allowed smarter operation of the machine as time progressed.  How?  Because the charts included the old and new settings of the machine, and better results were tied to settings.  At the beginning, adjustments would be slow, and sometimes the product variances increased as the worker tried out the machine.  Eventually, however, the system of machine, worker, and state chart knowledge would eventually converge until, if a variance started cropping up, the worker could be able to go to the state charts, look up that specific variance, and know to turn a dial two tick marks to the left to eliminate it.

What was essential was that, during the learning process, although the intermediate product was awful, progress was being made toward meeting the standard because there was, on the part of the worker, a determination to stamp out the errors because he had an attitude of zero tolerance toward them.  Because he had that attitude, and had the state charts to show he was making progress, management gave the worker permission to go through the man-machine-state chart learning process, knowing that, in the long run, the charts and worker would attain higher levels of production with the benefit of the product being of high quality.

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