title: Generating GPS activity spaces that shed light upon the mobility habits of older adults: a descriptive analysis.
abstract: BACKGROUND
  Measuring mobility is critical for understanding neighborhood influences on older adults' health and functioning. Global Positioning Systems (GPS) may represent an important opportunity to measure, describe, and compare mobility patterns in older adults.
  
  
  METHODS
  We generated three types of activity spaces (Standard Deviation Ellipse, Minimum Convex Polygon, Daily Path Area) using GPS data from 95 older adults in Vancouver, Canada. Calculated activity space areas and compactness were compared across sociodemographic and resource characteristics.
  
  
  RESULTS
  Area measures derived from the three different approaches to developing activity spaces were highly correlated. Participants who were younger, lived in less walkable neighborhoods, had a valid driver's license, had access to a vehicle, or had physical support to go outside of their homes had larger activity spaces. Mobility space compactness measures also differed by sociodemographic and resource characteristics.
  
  
  CONCLUSIONS
  This research extends the literature by demonstrating that GPS tracking can be used as a valuable tool to better understand the geographic mobility patterns of older adults. This study informs potential ways to maintain older adult independence by identifying factors that influence geographic mobility.
authors.forename: Jana A
authors.initials: JA
authors.lastname: Hirsch
authors.affiliation: Faculty of Health Sciences, Simon Fraser University, 8888 University Drive, Burnaby, British Columbia V5A 1S6, Canada. mwinters@sfu.ca.
authors.forename: Meghan
authors.initials: M
authors.lastname: Winters
authors.forename: Philippa
authors.initials: P
authors.lastname: Clarke
authors.forename: Heather
authors.initials: H
authors.lastname: McKay
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001955:British Columbia / Q000453:epidemiology; D003430:Cross-Sectional Studies; D005260:Female; D040362:Geographic Information Systems / Q000706:statistics & numerical data; D006184:Habits; D006801:Humans; D008297:Male; D009043:Motor Activity; D012111:Residence Characteristics / Q000706:statistics & numerical data; D016138:Walking / Q000523:psychology* / Q000706:statistics & numerical data