Establishing a framework of analysis for selective sorting and changing health gradients

Health inequalities research seeks to determine if changing health gradients may be due to the movement of differently healthy people between area types and/or social classes through a process of selective sorting. Because conclusions vary, in part because of different approaches employed, there is a need to establish an appropriate framework within which it is possible to determine whether and how spatial or social mobility contributes to changing spatial and social inequalities in health over time. In this paper, we present empirical examples demonstrating a methodological approach needed to determine aggregate changes in health, and discuss the results in terms of the impact of selective sorting on changing health gradients. Our empirical work illustrates that selective sorting through social mobility and migration can contribute to widening health inequalities in the population. We conclude that it is necessary to re‐aggregate microdata at the relevant time points of interest to determine changes in the population distribution of a particular health outcome. Simply establishing whether individuals vary in health by transition status may imply an impact on aggregate changes but does not demonstrate it.