“…During the past two decades, considerable attention has been devoted to biases present in the global or regional results from individual scales and to the relationships between the various individual scales (see, e.g., Evenden and Kohler (1976), Chinnery (1978), Der and others (1979), Herrmann and Nuttli (1982), Chung and Bernreuter (1981), Nuttli and Herrmann (1982), Chulick andHerrmann (1986), Ekstr?m andDziewonski (1988)). Some of these studies lead to differing or contradictory results.…”