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CU
SUM CHARTS
A Cu Sum Chart is a control
chart for variables data which plots the cumulative sum of the deviations
from a target. A V-mask is used as control limits. Because each plotted
point on the Cu Sum Chart uses information from all prior samples, it detects
much smaller process shifts than a normal control chart would. Cu Sum Charts
are especially effective with a subgroup size of one. Run tests should not
be used since each plotted point is dependent on prior points as they contain
common data values.
See also:
SPC Concepts
When
to Use a Cu Sum Chart
Interpreting
a Cu Sum Chart
For a general discussion
of Cu Sum charts, refer to any Statistical Quality Control textbook, such
as (Pyzdek, 1992a) or (Montgomery, 1991).
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