Table 5.

Regression Results Probit Estimation: Probability of HMO Membership

		N=38,185 χ253=6097.67 (p=0.0000)
	Coeffecient	Robust S.E.
Constant	−1.34**	(0.201)
Market penetration:
Percent penetration	3.47**	(0.51)
Penetration×Excellent healthL	−0.19	(0.17)
Penetration×Poor healthL	0.0052	(0.37)
Penetration×ADLsL	0.12	(0.088)
Penetration×IADLsL	−0.0054	(0.087)
Penetration×Social limitationsL	−0.019	(0.19)
Penetration×History of arthritisL	0.38*	(0.17)
Penetration×Number of other conditionsL	−0.103	(0.056)
IPA plan available	0.22	(0.15)
Health and functional status:
Excellent healthL	0.099*	(0.040)
Poor healthL	−0.085	(0.089)
ADLsL	0.0033	(0.0201)
IADLsL	0.0109	(0.020)
Social limitationsL	−0.051	(0.046)
History of arthritisL	−0.014	(0.0401)
History of cancerL	−0.11**	(0.037)
History of strokeL	−0.12*	(0.049)
Number of other conditionsL	−0.014	(0.014)
Demographics:†
AAPCC adjusters:
Ages 75 to 84	−0.094**	(0.030)
Age 85+	−0.17**	(0.044)
Male	0.017	(0.030)
Medicaid recipient	−1.21**	(0.068)
Nursing home resident	−0.24**	(0.092)
Other:
Less than high school education	−0.16**	(0.038)
Some college	−0.12**	(0.034)
Medigap policyL	−1.39**	(0.033)
Black	−0.00079	(0.0507)
Other nonwhite race	−0.036	(0.086)
Married	0.0808**	(0.0307)
Has a usual source of care	0.50**	(0.058)
Income<$10,000	−0.0012	(0.035)
Income $30,001–$50,000	−0.13**	(0.0403)
Income>$50,000	−0.29**	(0.065)
County variables:†
AAPCC rate (deviation from mean)	0.00097**	(0.00022)

^*p≤0.05,

^**p≤0.01;

^LLagged by one year;

^†Included in model but not reported in table: census region, rural/urban residence code, year, and missing data indicators for income, education, and Medigap.