Methods and related program product for assessing and optimizing metrology
instruments by determining a total measurement uncertainty (TMU) based on
precision and accuracy. The TMU is calculated based on a linear
regression analysis and removing a reference measuring system uncertainty
(U.sub.RMS) from a net residual error. The TMU provides an objective and
more accurate representation of whether a measurement system under test
has an ability to sense true product variation. The invention also
includes a method for determining an uncertainty of the TMU.