New challenges for the definition of functional geographies

Abstract

Studies from both Eurostat and the OECD shortly before the 2020/2021 Census ‘round’ concluded with one recommended approach to defining functional geographies (FGs). The question of which method to use in defining FGs for official statistics and policy has been superceded by challenging questions about the data to use for these definitions. One major concern stems from the decline of full Census-taking around the world, and in particular the reduced collection of the commuting data usually central to definitions of FGs. A more acute issue is that the 2020/2021 Census ‘round’ coincided with the Covid pandemic so that in many countries any commuting data collected reflects a brief and probably unique moment in time (eg. a total ‘lockdown’ in some countries). Defining FGs for official statistics and policy in the mid-2020s would ideally use data on ‘new normal’ patterns of commuting. Countries without a full register system or a new Census lack the necessary highly granular commuting data. This has led to increasing interest in the potential of call data from mobile phones as a surrogate for commuting data. This paper draws on research in Spain on the specific example of using data from mobiles to define a set of FGs. The approach taken is to evaluate the limits to the utility of mobile phone data by identifying a list of issues arising when using mobile phone data as a surrogate for Census commuting data, especially when seeking to define FGs