The debate about the nature of the urban rank size relationship continues for a variety of reasons. Several researchers thus take care to point out that the labeling of the rank size relationship as a law or a rule is incorrect. They argue that a statistical relationship, found only occasionally, and without theoretical foundation, has been elevated to the status of law. These concerns arise from several considerations. First is a concern for the margin of error which can be described graphically.
Log log graph paper affords wide latitude in plotting data.
Anyone who has had the experience of plotting a rank size curve knows how slight a difference even several thousands of population can make in the placement of a dot on the graph in the high and middle ranges of many sets of urban data. The largest cities, as well, usually deviate significantly from the values predicted by the formula or the straight line on a graph. This is the phenomenon known as the primate city. Attempts to accommodate the lower portion of the curve often displace the upper portion and vice versa. Applied to the simple rank size rule this means, for example, that instead of attempting to predict the size of the 100th largest city by dividing the population of the largest city by l00, we could, with equal logic, but with different results, predict the size of the largest city by multiplying the population of the city of rank 100 by 100.