DOES THE SIZE MATTER? Zipf's Law for Cities Revisited

Several authors (Berry 1970, Krugman 1996 or Eaton and Eckstein 1997, among many others) have experienced amazement about the accurate functioning of the law of “least effort” established by Zipf (1949) in most places. Cities, ranked by population, seem to follow almost exactly a log/log function, in which the logarithm of the "mass" (population, density, number of employees, etc.) correlates almost perfectly with the logarithm of the order of that mass. This log/log function, advanced by Pareto in the nineteenth century, has seduced quite a number of researchers, for its presence, hypothetically, both in natural phenomena (earthquakes, meteorites, living species, ...) and in the ones which derive from society (language, or distribution of cities), which has led to investigate its theoretical basis (Simon 1955, Brakmar et al. 1999, Gabaix 1999).