Vol. 7, No. 08
from Professor Cleary
The two divas' fascination with the 3-D appearance of the process diagrams apparently inhibited their ability to analyze their meanings more carefully.
Figure A illustrates a case of process that is in control, or one that is predictably doing the same thing, hour after hour, day after day. The central location is the same, the variability is the same, and the shape of the distribution is the same.
Figure B shows a picture of a process that is changing every hour. The second hour shows the central location moving up, and the variability becoming smaller. The third hour, central location recedes and variability increases. It is impossible to predict the future for such a process, and it of course represents a process that is out of control.
Much like the two quality divas.
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