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Aim / Objectives

Where, how far, and at what speed? The use of geospatial technologies in measuring and characterizing physical activity in behavioural health research. Asst/Prof Bryan J Boruff¹, Andrea Nathan² ¹School of Earth and Environment, ²Centre for the Built Environment and Health. Aim / Objectives.

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Aim / Objectives

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  1. Where, how far, and at what speed? The use of geospatial technologies in measuring and characterizing physical activity in behavioural health research Asst/Prof Bryan J Boruff¹, Andrea Nathan²¹School of Earth and Environment,²Centre for the Built Environment and Health

  2. Aim / Objectives To provide an overview of the current ‘state of science’ of GPS use in health research with a focus on physical activity • Current technology/uses • Case study of elderly adults in Perth: • Create alternative neighbourhood buffers, based on objective GPS walking data, which better represent the spatial extent in which older adults actually walk; • Explore the differences between the new neighbourhood buffers and standard buffers commonly used in the literature (i.e., circular, network, line-based network buffers) for built environment measures; and • Examine the relationship between land-use exposure and self-reported walking in older adults for each neighbourhood buffer.

  3. Social ecological model of influences on physical activity Pikora T, Giles-Corti B, Bull F, Jamrozik K, Donovan R. Developing a framework for assessment of the environmental determinants of walking and cycling. Soc Sci Med 2003;56:1693–703.

  4. Subjective Measures • Measuring Physical Activity – Self Reporting • Cons: • Memory recall • Ambiguous terminology • Lack of attention to instruction • Limited detail • Measuring the Built Environment – Surveys • Cons: • Perception based

  5. Built environment factor influencing walking for recreation Pikora T, Giles-Corti B, Bull F, Jamrozik K, Donovan R. Developing a framework for assessment of the environmental determinants of walking and cycling. Soc Sci Med 2003;56:1693–703.

  6. Measuring Physical Activity • GPS • Location • Time • Speed (derived) • Accelerometer • Proper acceleration – acceleration relative to freefall or acceleration felt by people and objects • Time • Heart rate • Heart beats per unit time • Time • *Mobile technology is the way forward

  7. Defining bouts (mode of transport) walking, running, bicycling, car, bus, gopher, etc. • GPS • Start and stop time • Sedentary time • Average speed • Accelerometer data • Ancillary information • Network link rules (speed direction) • Proximity to features Chung E, Shalaby A: A trip reconstruction tool for GPS-based personal travel surveys. Transportation Planning and Technology, Vol. 28, No. 5, pp. 381-401 (2005).

  8. Physical Activity and Location Measurement System (PALMS) http://ucsd-palms-project.wikispaces.com/

  9. GPS Technology in Physical Activity Research Troped PJ, Wilson JS, Matthews CE, Cromley EK, Melly SJ: The built environment and location-based physical activity. American Journal of Preventive Medicine 2010, 38(4):429-438.

  10. GPS Technology in Physical Activity Research Maddison R. Jiang Y, Hoorn SV, Exeter D, Mhurchu CN, Doery E: Describing patterns of physical activity in adolescents using global position systems and accelerometry. Pediatric Exercise Science 2010, 22:392-407.

  11. Case Study: Elderly Adults in Perth • The Active Living Study – a mixed-method, cross-sectional study conducted in 2009 – investigated active living among retirement village residents and the influence of village and neighbourhood environments • Survey to 325 residents in 32 retirement villages across Perth • 41 resident in 7 retirement villages agreed to participate in the sub-study (i.e. GPS and accelerometer) • UWA Human Research Ethics Committee (RA/4/1/2151)

  12. Case Study: Elderly Adults in Perth General buffering approaches Radial Network Network Bufferd - Population density, land use mix (accessibility, intensity, pattern), access to facilities, street patterns, traffic, crime, other (slope, greenness, lighting, etc. ) Brownson et al. 2009

  13. Aim / Objectives To provide an overview of the current ‘state of science’ of GPS use in health research with a focus on physical activity • Current technology/uses • Case study of elderly adults in Perth: • Create alternative neighbourhood buffers, based on objective GPS walking data, which better represent the spatial extent in which older adults actually walk; • Explore the differences between the new neighbourhood buffers and standard buffers commonly used in the literature (i.e., circular, network, line-based network buffers) for built environment measures; and • Examine the relationship between land-use exposure and self-reported walking in older adults for each neighbourhood buffer.

  14. Data and Source • Participants - GPS logs for 1 week - GlobalSat DG-100 - accelerometer data - Actigraph GT1M - surveys (physical activity, health, demographics) • Bouts - Classified using PALMS • GIS - road centre lines - Landgate - cadastre - Landgate - land use - Value Generals Office - destinations - SENSIS

  15. Alternative Buffering Techniques • Variable Weight Buffering • primarily in the field of ecology • developed to identify the land area on either side of a stream to repaired or maintain ecosystem integrity • based on stream size, presence of fish, land-use encroaching the stream or all of the above EPA , 2005

  16. Alternative Buffering Techniques • Variable Weight Buffering - method • mean percentage land-use exposure on GPS • weights were developed for all land-use to reflected ease of movement • 1 - average percent exposure to each land-use • land use/land cover grid was developed • weights were accumulated based on distance travelled (i.e., travel cost)

  17. Alternative Buffering Techniques “Visual examination of the GPS based walking trips revealed that participants were primarily exposed to recreational and park, institutional, and commercial (RIC) facilities” • RIC line buffers • Shortest route to all RIC facilities within 1000m • 50m buffer on either side • RIC polygon buffers • Convex hull of all RIC facilities within 1000m • RIC ellipse buffers • 1 SD ellipse highlighting directional trend within 1000m

  18. Median (Med) - measure of central tendency Inter Quartile Range (IQR) - difference between the 1st and 3rd quartiles - range of middle 50%

  19. Spearman’s correlation coefficients (rho) – nonparametric statistical relationship P-value (p) - < .05 reject the null

  20. Analytic Considerations

  21. Conclusion • Variable width buffers were most similar to circular buffers • RIC buffers skew towards commercial and recreational and park lu/lc (underestimating residential exposure) • All line based approaches showed similarity relationships in measuring lu/lc exposure • Institutional exposure similar across all buffer techniques • Although not presented here circular and variable width buffers provide the most predictive power in terms of walking for leisure

  22. Thank you and Questions Acknowledgement: The analysis in this paper was supported in part through a collaboration with the PALMS Project (UCSD-Palms-Project.wikispaces.com) at the University of California, San Diego. Funded by NIH/NCI Grant 1 U01 CA130771.

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