R&R Summary
The R&R Summary for the AIAG data which is generated by Mesa is
shown below:
Note that if we add the percentages on the
righthand column they add to well over 100%.
This is a peculiarity of the R&R approach and is caused
by the practice of calculating percentages of the standard
deviation. Since
standard deviations are not additive then the individual percentages
do not add to 100%. Note
that this is one aspect of the R&R approach which has been
criticised, and can easily lead to capable measurement systems being
labelled as inadequate.
Note:
When comparing the numerical results in the AIAG manual with those
generated by MESA you may find small differences (~1%).
This is because MESA uses the formulae given by Wheeler in
his book on industrial experimentation to calculate the values of d_{2}*,
rather than take them from an internal table.
