A Synthesis of Aggregation Methods for Multifacility Location Problems: Strategies for Containing Error

When solving a location problem using aggregated units to represent demand, it is well known that the process of aggregation introduces error. Research has focussed on individual components of error, with little work on identifying and controlling total error. We provide a focussed review of some of this literature and suggest a strategy for controlling total error. Consideration of alternative criteria for evaluating aggregation schemes shows that the method selected should be compatible with the objectives of the analyses in which it is used. Experiments are described that show that two different measures of error are related in a nonlinear way to the number of aggregate demand points (q), for any value of the number of facilities (p). We focus on the parameter q/p and show that it is critical for determining the expected severity of the error. Many practical implementations of location algorithms operate within the range of q/p where the rate of change of error with respect to q/p is highest.     

Conceptualizing Urban Inequalities as a Complex Socio-Technical Phenomenon

The United Nations World Social Report (2020) reveals that more than two thirds of the world's population live in countries where urban inequalities have increased in the last three decades. While urban inequalities are traditionally characterized as an economic issue, scholars are increasingly applying methods from geospatial analysis to study them. In the context of these advancements, it remains unclear what underlying perspectives are guiding decisions to concentrate on certain aspects of urban inequalities, while potentially ignoring others. We address this gap by reviewing the literature centered on the geospatial analysis of urban inequalities and identify three predominant research lenses from accessibility, distribution, and policy and stakeholder perspectives. As a primary contribution of this article, we connect the perspectives with ideas drawn from complexity theory to develop an overarching socio-technical framework for how urban inequalities emerge over space and time. While traditional scientific frameworks seek to increase knowledge through causality, complexity science acknowledges the inherent challenges in defining, understanding and solving complex problems such as urban inequalities, which has profound implications for their representation, modeling and interpretation. We critically reflect on the framework through key relational themes and insights drawn from the literature and close with considerations for future research.