Table 5. OLS Estimates of the Probability of Participating in Private Business for Sample Stratified by Physician Output: Plan A.

Variable	First Tercile		Second Tercile		Third Tercile
	Parameter Estimate	t-ratio	Parameter Estimate	t-ratio	Parameter Estimate	t-ratio
INTERCEPT	3.218*	2.56	2.563*	2.05	2.488*	2.00
APRVU	.144**	3.01	.411**	4.03	.726**	6.59
CPRVU	-.171**	-5.14	-.400**	-5.24	-.550**	-6.90
LAGPRCLM	-.001**	-3.27	-.001	-1.79	-.0002	-.39
AGE	.005**	3.16	.003*	2.15	.001	.55
AMASEX	.119*	2.09	.140	1.95	.063	.74
BORDCERT	-.100**	-2.83	-.099**	-2.88	.004	.11
FMG	.091*	2.50	.132**	3.68	.165**	4.55
GROUP	-.204**	-5.39	-.138**	-3.63	.032	.84
PARTNER	.139**	3.09	.037	.83	.095*	2.46
OTHER—EM	.121**	2.63	.086	1.52	.201**	3.05
PD—	.243**	3.67	.086	1.01	-.055	-.48
IM	.036	.53	-.027	-.40	-.351**	-4.65
OTHRSPEC	.112	1.94	.021	.37	-.088	-1.36
INPAHOSP	-.034	-.95	.086	1.89	.130**	2.65
WAGEINDX	.029	1.39	-.017	-.77	-.006	-.23
DOCPRCAP	198.520	.78	126.831	.50	205.131	.81
OUTPPRCP	.246	.58	.480	1.20	.063	.16
INPERCAP	-.001*	-2.06	-.0003	-1.15	-.001	-1.76
ENRBPRCP	-6.247*	-2.21	-7.613**	-2.69	-3.884	-1.46
PRCT—URB	-.0002	-1.07	-.0002	-1.17	.0003	1.85
TIME74	.086	.46	.216	1.24	.233	1.39
TIME75	-.011	-.05	.272	1.31	.232	1.10
TIME76	.359	.81	.479	1.17	.634	1.65
DFE	784		791		794
SSE	119.16		125.93		119.84
MSE	.15		.16		.15
F	11.18		8.96		8.71
PROB>F	.0001		.0001		.0001
R2	.25		.21		.20

One and two asterisks denote coefficients significantly different from zero at the 5 percent and 1 percent levels respectively (two-tailed tests).