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Table 1 Definition of terms

From: Exploring factors affecting individual GPS-based activity space and how researcher-defined food environments represent activity space, exposure and use of food outlets

Buffer type Shape Definition
Activity space (AS) [Calculated using GPS data] An area within which individual moves or travels during the course of their daily activities (i.e. everywhere a participant went for 7 days)
Straight-line buffer (SLB) [Calculated using questionnaire data] An area around a straight-line distance between two points of interest [18] (i.e. a buffer around a Euclidean distance between participant’s home and workplace)
Circular buffer around home/workplace (CBH/W) [Calculated using questionnaire data] A circular area around home (i.e. a circular buffer around a participant’s home/workplace)
Circular buffer around both home and workplace (CBHW) [Calculated using questionnaire data] An area formed by two circular buffers around home and workplace. It can be fused or two distinct circular areas
Street network buffer around workplace (SNBH/W) [Calculated using questionnaire data] An area that could be reached by a participant within a specified travel distance (i.e. 2 km, 4 km and 6 km) from home/workplace along a street network
Standard Deviational Ellipse (Lobstein et al.) [Calculated using GPS data] A measure of the trend of points (i.e. GPS points of participant’s movements) or orientation of an area (i.e. AS)
2 SDE refers to space around 95% of all GPS points of participants movements