Table 2.

Negative Binomial Regression Predicting the Number of Practice Sites per Physician

	Estimate	SE	95% LCLM	95% UCLM	P Value
Intercept	1.1833	0.0159	1.1521	1.2144	<.0001
Age (years)
<40	0.2884	0.0205	0.2482	0.3287	<.0001
40–49	0.2704	0.0181	0.235	0.3058	<.0001
50–59	0.1591	0.0189	0.122	0.1962	<.0001
≥60	Reference
Sex
Male	Reference
Female	−0.1544	0.0139	−0.1816	−0.1273	<.0001
IMG status
IMG	0.0268	0.015	−0.0026	0.0562	.0735
Non-IMG	Reference
Present employment setting
Self-employed solo practice	−0.4138	0.0225	−0.4579	−0.3696	<.0001
Two-physician practice	−0.32	0.0394	−0.3973	−0.2427	<.0001
Group practice	Reference
Medical school	−0.0603	0.0457	−0.1499	0.0293	.1873
State/local	−0.0749	0.0196	−0.1132	−0.0366	.0001
Federal	−0.1233	0.081	−0.2819	0.0354	.1279
Others	−0.0662	0.0162	−0.0979	−0.0345	<.0001
Primary Specialty
Non–primary care	Reference
Primary care	−0.2781	0.0138	−0.3052	−0.2511	<.0001
Dispersion	0.409	0.0066	0.3963	0.4221

A total of 19,451 cases were used; 665 cases were excluded because of missing values.
IMG, international medical graduate; LCLM, Lower Confidence Limit; SE, standard error; UCLM, Upper Confidence Limit.