Abstract
The rank-size rule for the population of cities is expressed by log P=-a log R+b where P is the population of a city, R is the rank of the population of the city P, and a and b are parameters. In this paper, I tried to apply this rule to the populations of each of 9 regions in Japan for 1960, 1965, 1970, and 1975. The rule was able to be successfully applied to those populations. Also, I was able to conclude that the system of population of cities in Japan was so homogeneous that the distribution of the population in cities in each of the regions of this country could be described by this same rank-size rule. Incidentally, when we try to perform this kind of examination, we should consider whether the rank-size rule can be simultaneously applied to the populations of cities within each region in a country. Therefore, I also discussed this problem theoretically. As a result of the theoretical consideration, I found the conditions for application of the rank-size rule to the populations of cities in each of the regions in a country, and I called the characteristic found in the rank-size rule the "decomposability" of this rule.
