TABLE 1.

Characteristics of the Surgeons and Hospitals in Which New and Experienced Surgeons Practice^‡

Covariate (% Unless Noted)	Surgeon-patients Before Sampling or Matching			Surgeon-patients After Sampling and Matching
	New	Experienced	P Value	New	Experienced	P Value
N surgeons	2119	8503		1820	1820
N patients	68,036	694,165		18,200	18,200
Surgeon characteristics
Years of practice at date of surgery	1.78	21.61	<0.0001	1.62	21.30	<0.0001
Operative volume per surgeon (mean)	32.1	81.6	<0.0001	31.2	111.6	<0.0001
Hospital characteristics
% in major teaching hospitals*	17.9	20.7	<0.0001	19.5	19.5	1.0000
% in nonteaching hospitals	46.2	39.4	<0.0001	45.3	45.3	1.0000
% in hospitals with nurse-to-bed ≥ 1.0	75.5	79.1	<0.0001	76.0	76.0	1.0000
% with high technology level†	61.8	67.8	<0.0001	61.4	61.4	1.0000
mean bed size	358.7	421.3	<0.0001	371.0	371.0	1.0000

^*Major teaching hospitals are defined as those with resident-to-bed ratios ≥0.25. Nonteaching hospitals are those with RTB = 0.

^†High technology level is defined as the provision of cardiothoracic surgery or organ transplantation services.

^‡Note. The left set of columns represents the practice distribution of all eligible new and experienced surgeons who had at least 10 cases and were practicing in the same hospitals. The right set of columns represents the random selection of 10 patients per new surgeon, and the experienced surgeon patients they were matched to. All covariates are weighted at the patient level.