In recent years, the TM [27] has become a
powerful technique for process/product quality
improvement. Taguchi proposed a robust design
strategy aimed at simultaneous optimization of
the mean and the variance of the response being
investigated. Taguchi suggested a summary
statistic that combines information about the
mean and variance into a single performance
measure, known as the signal-to-noise (S/N)
ratio. Taguchi found out empirically that S/N
ratios give the (near) optimal combination of the
factor levels, where the variance is minimum,
while keeping the mean close to the target value,
without using any kind of model.