Before measurement data, that is figures
and associated units of measurement, can be used, they must be converted
into information that carries a clear and unequivocal message. This can
be done by putting the data in the right context. For example, having measured
the diameter of a pin and found it equal to 9.950 mm, a measurement result
has been obtained but no conclusion can be made yet as to the necessary
action to be undertaken. By comparing this figure with the tolerance range
of the pin according to specifications – between 9.960 and 9.990 mm, it
can be seen that this particular pin is out of tolerance, i.e. it is not
conforming to specifications. Similarly, saying that s
for the machining process used to produce the same pin was found equal
to 0.008 mm is a piece of data that does not convey a clear message to
the manager. But comparing this figure to the tolerance range it becomes
clear that the range of variation of the diameter of the pins produced
by this process which corresponds to 6 s
is equal to 0.048 mm which is greater than the tolerance range (0.030 mm).
The conclusion is that the capability of this production process is not
adequate for the purpose and a more precise process should be found to
produce these pins.
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