| Short Run SPC is used in
batch production when the runs of any one
item are too short to run standard Statistical
Process Control.
The basic idea is to measure the deviation
from the standard size. For example if bars
of varying diameter are machined the control
charts would monitor the deviations from
the target bar diameter, rather than the
bar diameter.
The snag with this may be that the amount
of variation may vary from part to part.
One way of dealing with this is to use the
ZmR chart in which the deviation from the
target value is divided by the Standard
Deviation.
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