Hierarchy, central place theory and computational modelling

Abstract

The Central Place Theory (CPT) originates from the works of Walter Christaller (1933) in which he sets up a set of rules in terms of population threshold and commuting range for the provision of any specific service such as schooling or the running of a hospital. The model became very influential and guided the regional delineation of Estonia in the 1930ies and Sweden during the post-war years. In addition, from the methodological viewpoint, CPT can be considered as a starting platform in the complexity studies, by highlighting the relevance of hierarchies and regularities in the spatial organization of socio-economic activities. Interestingly, the issue of complexity taking form of hierarchies was examined about thirty years later by the Nobel Laureate Herbert Simon in 1962, by paving the way to the ongoing discussion on complexity vs. simplicity. Given this important role of hierarchic systems, in this study, we revisit the underlying principles of population threshold and commuting range as used in the CPT by comparing the delineation of municipalities (designed to follow the CPT) to the functional distribution and use of mobile phones. 1,2 million phones are followed for 24h in a unique data-material stored in the MIND database at Uppsala University. By estimating the location of each phone at each hour, the diurnal paths of peoples’ activities are included in a model of CPT. Using a self-organising algorithm; phones are made to gravitate towards each other for the formation of centres, where a k-value corresponding to a CPT threshold functions as the target value. The area from which the phone at any centre has come corresponds to the area that defines the range used in the CPT. Summing up: by comparing the areal delineation of municipalities to the modelled areas of phones we can test: a) to what extent the CPT works in a contemporary setting; and b) if our self-organisation modelling can be used to identify hierarchical regions/areas that capture the different activity needs.