Variety and the evolution of refinery processing

22 p.International audienceEvolutionary theories of economic development stress the role of variety as both a determinant and a result of growth. In this paper we develop a measure of variety, based on Weitzman's maximum likelihood procedure. This measure is based on the distance between products, and indicates the degree of differentiation of a product population. We propose a generic method, which permits to regroup the products with very similar characteristics values before choosing randomly the product models to be used to calculate Weitzman's measure. We apply the variety measure to process characteristics of oil refining. The results obtained for this technology show classic evolutionary specialization patterns that can be understood on the basis of niche theory. Here the changes in variety are related to changes in the range of the services the technology considered can deliver, range which plays a role similar to that of the size of the habitat of a biological species.Dans ce papier, les auteurs proposent une méthode générique permettant de mesurer la variété au sein d'une famille de technologies. Cette méthode de mesure de la variété est appliquée aux technologies du raffinage. Les résultats font apparaître des comportements classiques de spécialisation qui peuvent s'interpréter dans le cadre de la théorie des niches