Table 2 Participant characteristics with subgroup characteristics of students with all tests completed and without 8-week post-training tests completed

1st year/2nd year student

17 (63)/10 (37)

10 (37)/17 (63)

27 (50)/27 (50)

Age (years)

25.0 ± 3.6

25.1 ± 2.5

25.1 ± 3.1

Female

10 (37)

17 (63)

27 (50)

Left hand dominant

2 (7)

2 (7)

4 (7)

Pre-training skill test score (10-point maximum)

3.20 ± 1.48

2.21 ± 1.75

2.70 ± 1.68

Pre-training knowledge test score (40-point maximum)

17.1 ± 9.5

13.8 ± 9.6

15.4 ± 9.6

First-choice residency program

IM 6 (22)

GS 6 (22)

EM 5 (19)

Ortho 4 (15)

Peds 3 (11)

Others 2 (7)

Undecided 1 (4)

IM 7 (26)

Peds 4 (15)

EM 3 (11)

GS 3 (11)

FM 3 (11)

OB/GYN 3 (11)

Others 3 (11)

Undecided 1 (4)

IM 13 (24)

GS 9 (17)

EM 8 (15)

Peds 7 (13)

FM 4 (7)

Ortho 4 (7)

Others 7 (13)

Undecided 2 (4)

 Structured ultrasound hands-on training or lecture

0 (0)

0 (0)

0 (0)

 Unstructured ultrasound hands-on training or lecture

15 (56)

8 (30)

23 (43)

 Cardiac ultrasound on patients

1 (4)

0 (0)

1 (2)

 Observation of a cardiac ultrasound on patients

16 (59)

14 (52)

30 (56)

 Cardiac ultrasound on healthy volunteers

21 (78)

13 (48)

34 (63)

 Cardiac ultrasound on simulators

2 (7)

1 (4)

3 (6)

 Experience using HHU (Butterfly iQ)

4 (15)

4 (15)

8 (15)

Completion of pre-training self-study of the ASE online module

27 (100)

26 (96)

53 (98)

ASE online module review between immediate post-training tests and 8-week post-training tests

6 (22)

NA

NA

Review of textbooks or websites other than the ASE module between immediate post-training tests and 8-week post-training tests

11 (41)

NA

NA

Additional hands-on training between immediate post-training tests and 8-week post-training tests

0 (0)

NA

NA