Labeling local products without excluding: Hotelling's differentiation model revisited[Labéliser les produits locaux sans exclure : le modèle de différenciation de Hotelling revisité]

We propose an industrial economic model inspired by the Hotelling model that takes into account product quality and the spatial context to analyze the emergence of prices in a framework of competition and labeling of a local product (Protected Geographical Indication). We integrate the collectors' strategy by assuming that they establish a contract imposing on producers a minimum investment in the quality of their production practices. The study analyzes these strategies before and after the implementation of the quality label. This study also makes it possible to evaluate the effectiveness of the constraints (GI specifications) defined by the producer group and the public authority in improving product quality and the distribution of value between producers and collectors. We show how certain economic variables evolve in the presence or absence of the GI label: choice of the collector's supply perimeter, price level imposed by the collector on producers, level of investment in quality by producers. We show that public authorities and producer groups must anticipate the evolution of these variables in order to choose the different elements of the GI specifications to avoid perverse effects associated with their strategies, in particular, the exclusion of certain producers and/or unsatisfactory product quality with regard to social well-being.