Relative Stability and Density

Published in Chapter 6, 2021

This work from Chapter 6 is motivated by a desire to address the following questions: (1) how can mobility be understood as a characteristic of a place over time? (2) what are national the ripple effects of large global cities, such as London, in terms of population density and transience? (3) What are the relationships between population density and transience across five decades? To address both questions, this analysis uses historic, spatial data for the period 1971−2011 to create a relative temporal classification of small area geographies in England and Wales. This analysis provides an accessible benchmark for understanding the impact of mobility and development on places and is important for numerically grounded discussions of local inequality and polarisation.

This analysis classifies places in terms of population stability and density using quartiles and outliers. It does so by sorting all values into three main categories (low, average, high), with two additional categories for very low and very high cases (based on Tukey fences as used in Chapter 3). This is done because the continuous measures are spread across different ranges due to the differing spatial unit resolutions of the census throughout time and therefore, cannot be compared directly. Labels of high, average and low area used to compare places over different decades. Average values are defined as those within the interquartile range – otherwise stated, the range that contains fifty percent of the data that falls between the 25th and 75th percentile. The virtue of this approach is that it allows for a data-driven, yet simple and clear and most importantly comparable understanding of what is low or high. ‘Low’ denotes values that are lower than half of the observations; in the same spirit, ‘high’ denotes values that are higher than fifty percent of the data.

Note: the interactive map below covers England and Wales at the smallest level and will therefore take time to load. More on the analysis here.