Table 2. Outcomes of ESD according to the first and latter 20 sets.

	Total	Trainee A			Trainee B
		First period	Latter period	P value	First period	Latter period	P value
Number of lesions	80	20	20		20	20
Total operation time, min	73 ± 45	73 ± 49	66 ± 41	0.63	100 ± 48	55 ± 29	0.001
Self-completion rate, n (%)	78 (98)	20 (100)	20 (100)	n.a.	18 (90)	20 (100)	0.24
En bloc R0 resection, n (%)	80 (100)	20 (100)	20 (100)	n.a.	20 (100)	20 (100)	n.a.
Complications
Delayed bleeding, n (%)	2 (3)	0 (0)	0 (0)	n.a.	2 (10)	0 (0)	0.24
Perforation, n (%)	2 (3)	0 (0)	0 (0)	n.a.	2 (10)	0 (0)	0.24
Delayed perforation, n (%)	0 (0)	0 (0)	0 (0)	n.a.	0 (0)	0 (0)	n.a.

Continuous data are shown as the mean ± SD.