Continuous vs Continual

[Steven_S_Prevette@RL.gov]

I, myself, prefer the term "continual".  As has been pointed out,
"continuous" seems to imply a steady "ramp" change.  In the data and
processes I deal with, I very rarely see "ramp" changes in the data.
Usually the data being plotted exhibit relatively quick (within three
time intervals) steadying out at a new level following an improvement
action.

I do differ with the interpretation that the PDSA cycle is "continuous".
One cannot get around the cycle that fast to demonstrate a continual
ramp.  The very nature of the "Study" step implies we must wait some
period of time for the "do" step to take effect, so we can see the
result on the accompanying control chart.  I believe that application of
the PDSA cycle repetitively results in continual stair step improvement.

It is the American love of "reengineering", "instant pudding" and
wholescale replacement of machines at once that Dr. Deming advised
against.  

Steve Prevette
FDH ESH Planning and Performance
ASQ Certified Quality Engineer
steven_s_prevette@rl.gov
509-373-9371
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