Evaluation of Spatial Accessibility to Ohio Trauma Centers Using a GIS-Based Gravity Model

Wei Chen, PhDSenior Systems Programmer

Research Information Solutions and Innovations of Nationwide Children’s Hospital

2015 Ohio GIS ConferenceSeptember 21 - 23, 2015 | Hyatt Regency Columbus| Columbus, Ohio

Accessibility•The ability of receiving quality service by

traveling from one location to another.

What affects accessibility?Consider a child looking for a doctor

Distance Demand Quality of Service

Supply

Law of Gravitation

Distance

DemandQuality of Service

Supply

The Research Question•Identify areas in Ohio with Good and Poor

accessibilities.

Zip codes and counties in Ohio.

Can you visually find out areas with good accessibility?

•Build a GIS model:

GIS helps formalize and automate the process

Di

Sj

P = Diij β

di j

dij

Steps 4-1: Calculate population potential from demand to service.

Population site (Demand)

Service site (Supply)

Build a GIS model, cont.

TPj = i ijD d

− β

m

∑i=1

Steps 4-2: Sum up the total population potential from all demands to each service location.

Population site (Demand)

Service site (Supply)

Di

Sj

di j

Build a GIS model, cont.Steps 4-3: Calculate access potential of demand location to service location.

Di

Sj

di j

Population site (Demand)

Service site (Supply)

Build a GIS model, cont.

n

= ∑ Aij

j =1TAi

Di

dij

Steps 4-4: Sum up the total access of the demand location to all service locations.

Sj Population site (Demand)

Service site (Supply)

This is the final accessibility we are talking about!

Result 3-1:

Accessibility to regional trauma centers on the Zip Code Level.

Result 3-2:

Accessibility to regional trauma centers on the County Level.

Result 3-3a:

Underserved counties in terms of trauma care access.

Result 3-3b:

Underserved counties ranking.

Conclusions• Accessibility to trauma service is dramatically different

among Ohio counties.

▫ For example, Franklin county is 20 times more advantageous than Hocking county.

▫ The 10 most served counties are about 10 times more accessible to trauma services than the 10 most underserved counties.

• Areas with good access largely cluster near urban centers (3Cs).

• Out-of-state service centers complement some of the needs of access from Ohio population.