Measuring polycentric urban development: The importance of accurately determining the ‘balance’ between ‘centers’

In recent years, much research has been devoted to developing appropriate analytical frameworks to capture polycentric urban development (PUD). In a recent contribution to this journal, Bartosiewicz and Marcińczak (2020) present what is arguably the most comprehensive, comparative review to date of the degree to which different analytical frameworks produce consistent results. The purpose of this research note is to show why we believe parts of Bartosiewicz and Marcińczak's (2020) findings need nuance and qualification. Our starting point is that a useful comparison between different studies and measurement frameworks needs to consider the relevance of consistency in several key dimensions, two of which are particularly pertinent here: (1) the careful specification of what constitutes a ‘center’ in a polycentric urban system, and (2) the identification of the ‘balance’ between centers as a measure of the degree of polycentricity. Two brief empirical analyses of the degree of morphological polycentricity in Polish NUTS-3 areas and the Chinese city-regions along the ‘Yangtze Economic Belt’ are included. Finally, suggestions are provided to facilitate future comparative analyses of PUD.