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1. Background
Urban and transportation planning policies should reflect the most rigorous public health evidence available [1]. Encouragingly, natural experiments have begun to emerge that can provide rigorous causal evidence for the influence of the built environment on physical activity [2,3,4,5]. These natural experiments can be broadly grouped into (1) “built environment intervention” studies that involve built environment modification with pre-and post-modification measurement of physical activity with either the same or different pre- and post-samples; or (2) “residential relocation” longitudinal studies where changes in individuals’ built environment and physical activity are measured before and after they relocate to a different neighbourhood [6]. This paper focuses on the latter.
Studies taking advantage of residential relocation have found support for associations between changes in the built environment and physical activity [7,8,9,10,11,12]. A Western Australian study (“RESIDE”) investigating longitudinal changes in physical activity and neighbourhood built characteristics before and after residential relocation to new homes (approximately 2-3 years later) found that increases in objectively-measured residential density, self-reported park access, and number of recreational destinations were associated with increased reported transportation cycling among urban adults [8]. Increases in objectively-measured street connectivity with relocation was also associated with increases in recreational cycling [8]. In a separate analysis [7] from the same study, increases in the number of objectively-measured transportation destinations and perceived transportation-related walkability characteristics were associated with an increase in duration of transportation walking; additionally, increases in the number of objectively-measured recreational destinations and perceived recreation-related walkability were associated with increases in duration of neighbourhood-based recreational walking. Other residential relocation longitudinal studies have also found changes in street connectivity [9], availability of recreational facilities [10], population density [11] and walkability (“Walk Score®”) [12] to be associated with changes in physical activity, among U.S. adults.
Compared with cross-sectional studies, longitudinal residential relocation studies can provide more precise estimates of the built environment-physical activity relationship, including accounting for residential self-selection (i.e., an individual choosing to reside in a neighbourhood with specific characteristics that support their current lifestyle or behavioural preferences). This study design however, requires repeated intra-individual data collections before and after residential relocation which is resource intensive and vulnerable to attrition [7]. “Quasi-longitudinal” residential relocation studies offer an alternative approach to investigating temporal relations between the built environment...