Associate Professor of Geography

In several empirical studies of urban and regional growth, attempts have been made to estimate the impact Of migration as both causal and dependent variable. These studies have not, however, been very clear about how migration acts as a causal variable to induce employment growth or decline. The analysis in this paper is based on a microeconomic model of a firm making investment and job creation decisions in the face of uncertainty about its future labour supply. These decisions are related to the relative costs of over and undershooting the future labour supply and the extent to which short-term substitution is possible between labour and other inputs. Also discussed are the means by which a firm estimates its future labour supDly and the impact of migration on this. In a recent paper, the theoretical foundations of several empirical models of urban and regional growth have been examined.l There, i