  Zipf's law for cities is probably the most famous regularity in social
sciences. So much that, a hundred years of publication later, its status is not
clear: is it a law of social organisation? Is it an instrument of description
of city size distributions? Is it an element of validation of geographical
objects (cities and systems of cities in particular)? Empirical estimations of
the rank-size parameters are very numerous and contradict each other. In this
study, we present the results of a reproducible meta-analysis of the largest
pool of papers regarding this issue, obtained from the collection of data made
open and the construction of an online interactive application which allows the
reader to explore this literature. We find that a large part of the variations
observed in the measure of Zipf's coefficient is unnecessary as it comes from
the choice of different technical specifications in the way cities are defined,
whereas some of the current theories to explain the remaining share of
variations are challenged by our results.
