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Concluding comments
Access Matters!
Convenience of access to activities
job, school, healthcare, park, public service, shopping …
Access defines “location” Spatial
closing the gap
Application in Healthcare Access: HPSA designation
U.S. ranks behind in health peБайду номын сангаасformance
deep disparities in access to care and health outcomes
Distance Road network Transportation means
Primitive measures
Distance (time) from supply Simply potential model
Ai jSjdij
Supply-demand ratio within an area FCA with a radius/box FCA with a travel time range
k within a travel time range from j (catchment Cj). 1b. Compute the supply to demand ratio within Cj:
Rj Sj / Pk kCj
2a. For each demand location i, search all supply
j Zi
k Cj
Generalizing “distance decay”
as a continuous function
a power or exponential function a Gaussian function
as a discrete variable
dichotomous as in 2SFCA multiple as in E2SFCA
From S/D Ratio to FCA
Simply S/D Ratio FCA with a Radius
Improvements Within-unit variation Cross-border
Limitations Straight-line S-D beyond radius
2-step floating catchment area: 2SFCA
Scale availability at each supply location
Sum up accessible supplies around each demand location
2SFCA Recap
1a. For each supply location j, select all demand locations
locations j within the travel time range from i
(catchment Zi). 2b. Sum up the supply to demand ratios at these supply
locations:
Ai Rj (Sj/ P k)
j Zi
Medical Geography: Health Care Accessibility and Implications
Fahui Wang
Fred B. Kniffen Professor of Geography Louisiana State University
June 17, 2010 @ CNU
Contents
The issue of access GIS-based accessibility measures Optimization towards equal access Application in healthcare access
PHSA designation and late-stage cancer
a hybrid approach
a kernel density function a three-zone approach
Generalizing “distance decay”
Validation
Modeling actual supply-demand interactions
Subject to
S 1 S 2 . S n . S .
Value of optimization
Emphasizing the equality issue Identifying over- and under-capacity
of supply Guiding planning and public policy in
Where you are
Nonspatial
Who you are
Social justice and public policy
Measurement
How scarce are the services?
Supply vs. Demand (ratio)
How far are demands from supplies?
demand locations by adjusting the amounts of supplies at given supply locations.
A Quadratic Programming Approach
m n
min (
Sjdij
a)2
V i1 j1
j
m
where Vj Dkdkj k1
Individual travel behavior Aggregated travel pattern
Optimization
Towards equal accessibility Formulated as a planning problem minimizing accessibility gaps among
Access Matters!
Convenience of access to activities
job, school, healthcare, park, public service, shopping …
Access defines “location” Spatial
closing the gap
Application in Healthcare Access: HPSA designation
U.S. ranks behind in health peБайду номын сангаасformance
deep disparities in access to care and health outcomes
Distance Road network Transportation means
Primitive measures
Distance (time) from supply Simply potential model
Ai jSjdij
Supply-demand ratio within an area FCA with a radius/box FCA with a travel time range
k within a travel time range from j (catchment Cj). 1b. Compute the supply to demand ratio within Cj:
Rj Sj / Pk kCj
2a. For each demand location i, search all supply
j Zi
k Cj
Generalizing “distance decay”
as a continuous function
a power or exponential function a Gaussian function
as a discrete variable
dichotomous as in 2SFCA multiple as in E2SFCA
From S/D Ratio to FCA
Simply S/D Ratio FCA with a Radius
Improvements Within-unit variation Cross-border
Limitations Straight-line S-D beyond radius
2-step floating catchment area: 2SFCA
Scale availability at each supply location
Sum up accessible supplies around each demand location
2SFCA Recap
1a. For each supply location j, select all demand locations
locations j within the travel time range from i
(catchment Zi). 2b. Sum up the supply to demand ratios at these supply
locations:
Ai Rj (Sj/ P k)
j Zi
Medical Geography: Health Care Accessibility and Implications
Fahui Wang
Fred B. Kniffen Professor of Geography Louisiana State University
June 17, 2010 @ CNU
Contents
The issue of access GIS-based accessibility measures Optimization towards equal access Application in healthcare access
PHSA designation and late-stage cancer
a hybrid approach
a kernel density function a three-zone approach
Generalizing “distance decay”
Validation
Modeling actual supply-demand interactions
Subject to
S 1 S 2 . S n . S .
Value of optimization
Emphasizing the equality issue Identifying over- and under-capacity
of supply Guiding planning and public policy in
Where you are
Nonspatial
Who you are
Social justice and public policy
Measurement
How scarce are the services?
Supply vs. Demand (ratio)
How far are demands from supplies?
demand locations by adjusting the amounts of supplies at given supply locations.
A Quadratic Programming Approach
m n
min (
Sjdij
a)2
V i1 j1
j
m
where Vj Dkdkj k1
Individual travel behavior Aggregated travel pattern
Optimization
Towards equal accessibility Formulated as a planning problem minimizing accessibility gaps among