Table 5 Selected correlations of attributes with respect to referral frequency. The p-value for all correlations is less than 0.01, except for the ones with an asterisk

HCPCS: Initial Hospital Care

0.46

Number of Hospital Affiliations

0.43

Number of HCPCS Beneficiaries

0.33

Relative Procedure Volume

0.26

HCPCS: X-ray Exam of Abdomen

0.24

Number of Rx Beneficiaries

0.23

Internal Medicine and Cardiovascular Disease

0.22

Diagnostic Radiology

0.21

Family Medicine

−0.20

Obstetrics and Gynecology

−0.16

Number of Fellowships

0.10

Negligible Correlations

Hospital Score

−0.02

Patient Review Ratings

[−0.01,0.01]^*

Number of Patient Reviews

−0.01

Number of Accepted Insurances

0.02

Years of Experience

0.01

Medical School Rank

0.03

Individual Insurers

[−0.4,0.5]^*

Residency Rank

0.01^*