Zipf’s and Gibrat’s laws for migrations

This paper analyses the evolution of the size distribution of the stock of emigrants in the period 1960-2000. Has the distribution of the stock of emigrants changed or has there been some convergence? This is the question discussed in this work. In particular, we are interested in testing the fulfillment of two empirical regularities studied in urban economics: Zipf’s law, which postulates that the product between the rank and size of a population is constant; and Gibrat’s law, witch states that growth rate of a variable is independent of its initial size. We use parametric and non-parametric methods and apply them to absolute (stock of emigrants) and relative (migration density, defined as the quotient between the stock of emigrants of a country and its total population)measurements.