As Stewart (1958) has argued, the rank-size rule may be viewed as a special case of the Pareto distribution in which b = -1. The rule may therefore be regarded as an empirical finding rather than a theoretical or logical necessity. We should thus gauge the usefulness of the rank-size rule by the degree to which it helps us to generalize observations on actual settlement distributions. Studies by Allen (1954) and Clark (1967) show considerable variations about the values of b = -1.00. Egypt (b = -.1.77) or Portugal (, = -1.43) show steeply-sloping curves in which city size falls off very rapidly with rank. Conversely, New Zealand (b = -0.74) and Norway (b = -0 .85) have much flatter curves than expected. Table 4.4 shows the size distribution of cities with different b values for comparison. The distributions are graphed in Figure 4.9.