Table 1.

Sample Description

		Purchase of Robotic Surgical Systems
	Total	Yes	No	P Value
Overall	3791 (100%)	78 (2.06%)	3713 (97.94%)
Purchase of robotic surgical system before				<0.001
Yes	250 (6.59%)	20 (8.00%)	230 (92.00%)
No	3541 (93.41%)	58 (1.64%)	3483 (98.36%)
Number of beds				<0.001
>300	876 (23.11%)	52 (5.94%)	824 (94.06%)
≤300	2915 (76.89%)	26 (0.89%)	2889 (99.11%)
Control type				<0.001
Nonprofit	2044 (53.92%)	66 (3.23%)	1978 (96.77%)
Other control type	1747 (46.08%)	12 (0.69%)	1735 (99.31%)
Teaching hospital				<0.001
Yes	213 (5.62%)	14 (6.57%)	199 (93.43%)
No	3578 (94.38)	64 (1.70%)	3514 (98.21%)
Patients’ average age				0.140
Mean (SD)		45.08 (13.68)	47.91 (16.91)
Proportion of females (%)				0.850
Mean (SD)		58.47 (6.07)	58.26 (10.11)
Proportion covered by private payers (%)				<0.001
Mean (SD)		39.54 (15.22)	29.72 (20.22)
The hospital’s directly relevant surgery volume in the previous year				<0.001
Mean (SD)		627 (359.67)	222.52 (263.23)
Herfindahl index				0.985
>2500 (highly concentrated market)	2968 (78.29%)	61 (2.06%)	2907 (97.94%)
≤2500 (not highly concentrated market)	823 (21.71%)	17 (2.07%)	806 (97.93%)
Existing robotic surgical systems (excluding the hospital’s own) in the same market area				0.139
Yes	995 (26.25%)	26 (2.61%)	969 (97.39%)
No	2796 (73.75%)	52 (1.86%)	2744 (98.14%)
The market-level surgery volume (excluding the hospital’s own) in the previous year				0.247
>50,000 (high volume)	607 (16.01%)	12 (1.98 %)	595 (98.02%)
1–50,000 (not high volume)	1954 (51.54%)	47 (2.41%)	1907 (97.59%)
0	1230 (32.45%)	19 (1.54%)	1211 (98.46%)
Year				<0.001
2003–2005	1261 (33.26%)	13 (1.03%)	1248 (98.97%)
2006–2008	1257 (33.16%)	23 (1.83%)	1234 (98.17%)
2009–2011	1273 (33.58%)	42 (3.30%)	1231 (96.70%)