New Methods For Measuring Access To Food Sources

1. New Methods For Measuring Access To Food Sources Research to Policy Briefing with Food Standards, Australia/New Zealand September 6, 2007 Philip Hurvitz, PhCUrban Form LabCollege of Architecture & Urban PlanningUniversity of Washington

2. Overview • Importance of location in public health • Typical representations of location • Fine-scaled approaches to representation and analysis of location • Future directions in spatial representations for public health surveillance and intervention Slide 2 (of 19) PMH

3. Overview • Importance of location in public health • Typical representations of location • Fine-scaled approaches to representation and analysis of location • Future directions in spatial representations for public health surveillance and intervention Slide 3 (of 19) PMH

4. Importance of location in epidemiology & public health • “…the curse causeless shall not come” –Proverbs 26:2 • Exposure to disease-causing conditions and agents is spatially and temporally bound • Epidemiology is fundamentally a spatial science • Has medical scienceignored location inrecent decades? Slide 4 (of 19) PMH

5. Importance of location in epidemiology & public health • Epidemiology and public health are interested in population-wide effects, … but … • Population-wide effects can only be ascertained from individual-level measurements • GIS allows the measurement of individual characteristics within an explicitly spatial context • If location is an important factor in a public health issue, GIS should be incorporated as a data management and analysis tool Slide 5 (of 19) PMH

6. Overview • Importance of location in public health • Typical representations of location • Fine-scaled approaches to representation and analysis of location • Future directions in spatial representations for public health surveillance and intervention Slide 6 (of 19) PMH

7. Obesity by state, 2006 http://go.worldbank.org/DL057HBF30 http://www.cdc.gov/nccdphp/dnpa/obesity/trend/maps/ Typical representations of location • Area-based representations are popular • Easily created from simple statistical tables and base map geographic files Slide 7 (of 19) PMH

8. Typical representations of location • Large area-based maps tell us little about the exposure → disease causal chain • Aggregated data ignore the spatial nature of individualistic exposure (MAUP) this tract has FF density of 0 this tract is high in FF density Slide 8 (of 19) PMH

9. Overview • Importance of location in public health • Typical representations of location • Fine-scaled approaches to representation and analysis of location • Future directions in spatial representations for public health surveillance and intervention Slide 9 (of 19) PMH

10. PHSKC data Fine-scaled approaches to representation and analysis of location • “Public” data sources can be used for location source data Yellow Pages data Slide 10 (of 19) PMH

11. Fine-scaled approaches to representation and analysis of location • Geocoding of individual locations can be useful • Knowledge of specific locations of agents of exposure may be informative beyond simple spatial aggregation does this tract have an effective FF densityof 0? this tract is high in FF density Slide 11 (of 19) PMH

12. Fine-scaled approaches to representation and analysis of location • Use of newer spatial analysis methods • Interpolation techniques (e.g. kernel densityestimator, KDE) • can estimate exposures at any location in space • not limited to arbitrary administrative boundaries this tract has arelatively high effective FF density Slide 12 (of 19) PMH

13. Fine-scaled approaches to representation and analysis of location • Use of fine scaled data sources • Tax-lot-level data are detailed and varied • Variation at the household-unit population level is maintained and can be used for analytical purposes Slide 13 (of 19) PMH

14. Fine-scaled approaches to representation and analysis of location • Census data lack detail and variation • Within-tract variation is lost as geometries become larger and more aggregated • Boundaries may lack meaning Slide 14 (of 19) PMH

15. Fine-scaled approaches to representation and analysis of location • Fine-grain disaggregate data give much greater statistical power for linking SEP, exposure, and disease Rank order by value Rank order by value Slide 15 (of 19) PMH

16. Fine-scaled approaches to representation and analysis of location • Measurement of physical activity and location in real time (1 s, 3-7 m precision) Slide 16 (of 19) PMH

17. Fine-scaled approaches to representation and analysis of location • Measurement of energy balance in real time, providing information about healthy food choice and physical activity enhancing locations Slide 17 (of 19) PMH

18. Overview • Importance of location in public health • Typical representations of location • Fine-scaled approaches to representation and analysis of location • Future directions in spatial representations for public health surveillance and intervention Slide 18 (of 19) PMH

19. Future directions in spatial representations for public health surveillance and intervention • Partnerships among researchers, public health agencies, local governments, and health care providers for surveillance and intervention • Transdisciplinary research teams (urban planning, epidemiology, computer science • Spatially explicit data sources available from top down and generated from bottom up • New analytical methods to handle multiple and high-resolution data sources Slide 19 (of 19) PMH