Table 2.

Baseline characteristics by study.

Variables	Study 1	Study 2	Study 3	Study 4
	Overall n = 81	Overall n = 202	Overall n = 129	Overall n = 190
Gender (% Female)	28.4%	59.0%	2.2%	65.8%
Mean age (SD)	49.4 (9.9)	46.2 (22.8)	49.8 (8.8)	50.4 (n/a) *
Post-residency and fellowship (% years)
0–1	2.5%	9.1%	1.4%	0.0%
2–5	16.1%	24.7%	6.5%	4.2%
6–10	19.8%	17.7%	16.6%	16.3%
11–20	19.8%	34.4%	45.3%	33.2%
21+	42.0%	14.0%	30.2%	46.3%
Practice size (% of physicians associated with practice)
1–3	46.9%	24.2%	33.8%	44.7%
4–10	25.9%	36.1%	36.0%	34.7%
10+	27.2%	39.7%	30.2%	20.5%
Physician type (%)
Generalist	0.0%	40.0%	0.0%	100%
Specialist	100.0%	60.0%	100.0%	0%
Single Specialty Practice (%)	59.3%	57.3%	85.5%	72.1%
Practice type (%)
Group/Staff	n/a	66.2%	85.5%	93.2%
IPA/Network	n/a	6.3%	7.3%	6.3%
Mixed/other	n/a	27.6%	7.3%	0.5%
Practice Ownership (%)
Physician–Physician group	71.6%	25.0%	89.2%	n/a
Hospital–Academic Medical Center	17.3%	60.9%	6.5%	n/a
Community Health Center	3.7%	7.3%	3.6%	n/a
Other	7.4%	6.8%	0.7%	n/a
Employed by practice (% Yes)	77.8%	93.3%	66.2%	73.7%
Average days worked per week (%)
1–3	2.5%	10.9%	0.0%	n/a
4	33.3%	22.9%	10.9%	n/a
5+	64.2%	66.2%	89.1%	n/a
Proportion of all patients covered by
Medicare	39.2%	7.3%	47.4%	32.1%
Commercial	46.6%	44.6%	41.2%	52.4%
Medicaid	7.7%	40.6%	6.4%	7.6%
Self-pay	4.9%	5.2%	3.7%	5.8%
Other	1.6%	2.8%	1.3%	2.1%

SD: Standard Deviation; n/a: information is not available; * estimated average age, based on age groups.