The dynamics of urban population.

The relative roles of natural increase and migration in determining the long-term dynamics of an urban population are considered. "Rogers' model is used to represent the simultaneous growth of a multiregional population. Exploiting the mathematical structure of the resulting system of difference equations, a perturbation theory for demographic models [is] outlined. This theory provides useful tools for analysing the sensitivity of stable population distribution and rate of growth to changes in the fundamental demographic parameters. With respect to the conventional approach to sensitivity analysis, it does not require the sometimes cumbersome calculation of matrix derivatives." A numerical example is given to demonstrate the method. (SUMMARY IN FRE AND ITA)