Table 3 Cumulative summation score and slope score of the learning curve in single-port thoracoscopic lobectomy for junior thoracic surgeon

1

1.7

1.3

21

16.7

0.1

41

15.7

 − 0.5

2

2.4

1.3

22

17.4

0.1

42

16.4

 − 0.5

3

3.1

1.2

23

17.1

0.0

43

18.1

 − 0.5

4

3.8

1.1

24

17.8

0.0

44

17.8

 − 0.5

5

6.5

1.0

25

17.5

 − 0.1*

45

17.5

 − 0.6

6

6.2

1.0

26

17.2

 − 0.1

46

17.2

 − 0.6

7

6.9

0.9

27

17.9

 − 0.1

47

16.9

 − 0.6

8

8.6

0.8

28

17.6

 − 0.2

48

16.6

 − 0.6

9

10.3

0.8

29

17.3

 − 0.2

49

16.3

 − 0.6

10

12

0.7

30

18

 − 0.3

50

17

 − 0.6

11

11.7

0.6

31

17.7

 − 0.3

51

16.7

 − 0.6

12

11.4

0.6

32

17.4

 − 0.3

52

16.4

 − 0.6

13

12.1

0.5

33

17.1

 − 0.3

53

16.1

 − 0.6

14

13.8

0.5

34

16.8

 − 0.4

54

15.8

 − 0.6

15

14.5

0.4

35

16.5

 − 0.4

55

15.5

 − 0.6

16

15.2

0.4

36

16.2

 − 0.4

56

15.2

 − 0.5

17

15.9

0.3

37

15.9

 − 0.4

57

14.9

 − 0.5

18

16.6

0.2

38

16.6

 − 0.5

58

14.6

 − 0.5

19

16.3

0.2

39

16.3

 − 0.5

59

14.3

 − 0.5

20

17

0.1

40

16

 − 0.5

60

14

 − 0.5