1. The Herfindahl Index is calculated as the sum of the squares of the shares of beds for all hospitals within a fifteen-mile radius of the hospital. By construe-tion, this index is higher if a particular hospital dominates a geographic area. For example, if a hospital is the only provider within a fifteen-mile radius, the Herfindahl index equals one. The index declines as the number of neighboring hospitals increases. For example, if a hospital has nine neighbors of the same size within a fifteen-mile radius, the Herfindahl index would be equal to 0.1. For further discussion , see
Tirole J.
,
The Theory of Industrial Organization
(
Cambridge, Mass.
:
The MIT Press
,
1990
),
221
-
223
.
2. Gaskin D.
,
Hadley J.
,
“The Impact of HMO Penetration on the Rate of Hospital Cost Inflation, 1984-1993,”
IWP #95-004 (
Washington
:
Institute for Health Care Research and Policy, Georgetown University
,
April 1996
).
3. The Evolution of Support for Safety-Net Hospitals