Some extensions and limitations of frequency domain experiments

We present three extensions of the frequency domain approach proposed by Schruben and Cogliano (1987). The first is the assignment of multiple frequencies to input factors. The frequency selection in this case is nearly identical to that of one frequency per factor. The second extension is the use of the time series of batch means to flatten the noise spectrum and make the identification of peaks in the output spectrum easier. Finally, we show that using common random numbers (as suggested in Schruben and Cogliano, 1987) for the signal and noise runs do indeed tend to decrease the peaks in the noise spectrum and also facilitate factor identification.