Acceleration response spectral ratios were analyzed to examine their statistical characteristics. First, the probability distribution of the ratios was analyzed, and equations for the probability density functions, mean values, standard deviations, and percentiles were shown. Second, the above-mentioned statistics were estimated using accelerometer arrays of the Chiba and SMART-1 databases. Then, the relationships between these statistics and the station separations, frequencies and damping ratios were analyzed. Finally, based on the 50^<th> and 95^<th> percentiles, the differences between the response spectra at two different sites due to future earthquakes were discussed.
