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Table 2 Description of spatial exposure measures from extracted relationships and associations

From: Food environments and dietary intakes among adults: does the type of spatial exposure measurement matter? A systematic review

Concept Measure Description Number of relationshipsa Number of associations (n = 202)b % of associations significant in the expected or unexpected directionc
Availability Continuous density Euclidean kernel density estimation A continuous density surface across a given area based on defined Euclidean kernels calculated using a probability density function 3 18 61.1
Variety Road network buffer Number of different outlets belonging to the same outlet category type within a defined area calculated using a road network radius from a reference location 2 2 50
Count Road network buffer Number of outlets within a defined area calculated using a road network radius from a reference location 26 68 44
Euclidean buffer Number of outlets within a defined circular area calculated using a straight line radius from a reference location 5 20 40
Presence Euclidean buffer Binary presence/absence (1, 0) of outlets within a defined circular area calculated using a straight line radius from a reference location 8 11 9
Road network buffer Binary presence/absence (1, 0) of outlets within a defined area calculated using a road network radius from a reference location 5 12 8
Relative density Euclidean buffer count/10,000 population Number of outlets relative to another quantity within a defined circular area calculated using a straight line radius from a reference location 9 13 7.7
Diversity Euclidean buffer Number of different outlet category types within a defined circular area calculated using a straight line radius from a reference location 1 1 0
Retail food environment index Euclidean buffer Ratio of different outlet types within a defined circular area calculated using a straight line radius from a reference location 1 1 0
Accessibility Proximity Euclidean distance Straight line distance from a reference location to the nearest outlet 7 11 36.4
Road network distance Road network distance from a reference location to the nearest outlet 36 38 21 (2.6)
Average proximity Road network distance Average road network distance from a reference location to all outlets 7 7 (28.6)
  1. aCount of the total number of relationships that employed a particular measure
  2. bDunn (2012) [43] did not report on the technique used to determine proximity, count within a 1 mile buffer, and count within a 3 mile buffer. Therefore, these associations (n = 3) were excluded from the table
  3. cThe percentage of unexpected associations is placed in brackets