A method for monitoring performance of an advanced process control system
for at least one process output includes calculating a variance of a
prediction error for a processing performance and/or a probability for
violating specification limits of the processing performance of the at
least one process output. If the variance of the prediction error is
calculated, the method also includes calculating a model health index. If
the probability for violating specification limits is calculated, the
method further includes calculating a process health index.