Table 2.

Measures and Sources

VARIABLE	MEASURE	SOURCE
Hospital performance
Market share per bed	Log of percentage of hospital inpatient days divided by total market inpatient days adjusted for hospital bed size	AHA Annual Survey
Cost per discharge	Total hospital inpatient costs divided by total hospital discharges adjusted for case mix index	Center for Medicare and Medicaid Services
Return on assets	Profit divided by total assets	Center for Medicare and Medicaid Services
Duplicated services	Number of high-tech services that both a focal hospital and its competitor provide	AHA Annual Survey
Differentiated services	Number of high-tech services that a focal hospital provides but its competitor does not	AHA Annual Survey
Market structure
Geographic distance	Log of distance in miles between local hospital and each of its competitors in a local market	AHA Annual Survey, arcGIS
Size asymmetry	Log of ratio of local hospital bed size over each of its competitors in a local market	AHA Annual Survey
Market competition	1 – HHI within county	AHA Annual Survey
Population density	Log of population of county in thousands divided by areas in miles	Area Resource File
Community munificence	Log of per capita income in thousand within county	Area Resource File
Specialists per 1000 population	Log of number of specialist physicians per 1000 population	Area Resource File
Managed care penetration	Percentage managed care members over population in state	Bates White Economic Consulting
Control variables
Multihospital membership	0: No, 1: Yes	AHA Annual Survey
Ownership for non-profit	0: No, 1: Yes	AHA Annual Survey
Bed size	Log of staffed beds	AHA Annual Survey
Case mix index	Medicare case mix index	Center for Medicare and Medicaid Services