“…(3). However, his estimates were not statistically meaningful, since a frequency band mean was not taken, as was pointed out by Hayashi (1973), Tsay (1974) andPratt (1976). On the other hand, Hayashi (1971Hayashi ( , 1977bHayashi ( , 1981b's method enables one to estimate spacetime cross spectra by use of time spectral analysis methods such as the lag correlation method, the direct Fourier transform method and the maximum entropy method depending on the length of the record.…”