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aries. Intuitively, one may think of HRRs as representing the geographic level at which “back end” services such as invasive surgery are received.



For a partial list of references, see Alter et al. (1999); Blustein and Weitzman (1995); Chen et al. (2001); Gornick et al. (1996); Peterson et al. (1997); Rathore et al. (2000); and references therein.


Also see Skinner et al. (2001) for measures of morbidity (i.e., heart attacks, stroke, gastrointestinal bleeding, colon cancer, lung cancer) across HRRs as developed in the Dartmouth Atlas of Health Care (Wennberg and Cooper, 1999).


The “flat of the curve” refers to a region where the marginal health intervention has zero impact on outcomes. For economists, this corresponds to the region of zero marginal product. This notion is formalized by Skinner and colleagues (2001); and Wennberg et al. (2002).


It is possible that much of the observed variation reflects random deviations from identical practice patterns across communities (Diehr, Cain, Kreuter, and Rosenkranz, 1992). While this possibility must be considered for smaller samples, the very large samples in the Medicare claims data preclude this explanation; also see McPherson, Strong, Epstein, and Jones (1981).


In statistical analysis, controlling implicitly for selection using the percentage of HMO enrollees in the area has not affected empirical estimates. Beginning in 2000, HMOs were expected to report hospital procedures to the Centers for Medicare and Medicaid Services, suggesting better data on managed care enrollees in the future.


For further details on the construction methods, see


Illness has been controlled for by using age-sex-race-specific mortality and hospitalization rates for five conditions: hip fracture, cancer of the colon or lung treated surgically, gastrointestinal hemorrhage, acute myocardial infarction, or stroke. These conditions were chosen because hospitalization for them is a proxy for the incidence of disease. The cost of living indices were computed by using nonmedical regional price measures. Doing so avoids contaminating the analysis with physician workforce or hospital market conditions.


Values of the index over 60 are considered high. It means that 60 percent of the members of one group would need to move to a different neighborhood in order for the two groups to be equally distributed.


The isolation index measures the extent to which minority members are exposed only to each other, and is calculated as the minority-weighted average of the minority proportion in each area.


States are used instead of HRRs to increase statistical power.


Population weights are for the state-specific African-American and non-African American population for both men and women, not just men alone.


We are grateful to Melinda Pitts for pointing out this correlation to us.


Furthermore, the means for beta-blocker use differ substantially between the two studies—56 percent versus 72 percent, suggesting different criteria may have been used to determine appropriateness.


When Washington, DC, is included in the sample, the observed (unweighted) negative correlation disappears. This is because DC is an “outlier”—the population is 61 percent African American, but exhibits 93 percent beta-blocker use.


Jenks et al. (2000) rank states on the basis of whether interventions that are known to be correct were administered for conditions such as AMI, heart failure, stroke, pneumonia, screening for breast cancer for women aged over 53, and eye exams and lipid profiles for diabetics.

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