Table 3.

IV and OLS Estimates of Usual Source of Care

		Coefficients (p-values) by Estimation Method
		OLS Regression		IV Regression
Independent Variable	Mean Value	Beta	p-value	Beta	p-value
Distance to nearest safety net provider (miles)a
Community Health Center (CHC)	12.63	0.0001	0.85	−0.002	0.52
Safety Net Hospital (SNH)	14.51	−0.0004	0.44	−0.01	0.03
Age (years)	31.7	−0.02	0.00	−0.01	0.00
Age-squared	1,225.8	0.0002	0.00	0.0002	0.00
Annual family income ($10,000s)	21.9	0.000001	0.03	0.00	0.02
Education (years)	11.9	0.003	0.42	0.003	0.38
Femaleb	0.511	0.14	0.00	0.14	0.00
Race and ethnicityb
African American	0.163	−0.02	0.30	−0.09	0.002
Hispanic	0.240	−0.07	0.02	−0.11	0.001
Other race	0.050	−0.05	0.27	−0.09	0.03
Interviewed in Spanish	0.160	−0.11	0.0017	−0.13	0.0004
Health statusb
Excellent or very good	0.573	−0.02	0.34	−0.01	0.82
Good	0.260	−0.06	0.02	−0.06	0.04
Family structureb
Single person w/o children	0.372	−0.05	0.04	−0.08	0.00
Single person w/children	0.180	0.03	0.28	0.00	0.86
Married couple, no children	0.112	−0.03	0.33	−0.03	0.34
Community Typeb
Small metro	0.032	−0.07	0.08	−0.03	0.38
Nonmetro	0.111	0.11	0.0001	0.24	0.00
Risk Preferenceb
Strong risk taker	0.194	−0.03	0.15	−0.02	0.35
Moderate risk taker	0.273	0.00	0.84	0.00	0.77
Risk preference missing	0.060	0.00	1.00	−0.01	0.69
Intercept		0.74	0.00	0.88	0.00
R-squared		0.097		0.102

^aStraight-line distances calculated from latitude and longitudes of population centroids of 5-digit zip codes.

^bDichotomous variable of uninsured persons and safety net providers.