Total score correlation
| Video | Grader score: n/40 | |||||
| A | B | C | D | Mean | SD | |
| 1 | 2 | 0 | 1 | 3 | 1.50 | 1.29 |
| 2 | 0 | 1 | 0 | 1 | 0.50 | 0.58 |
| 3 | 14 | 12 | 14 | 14 | 13.50 | 1.00 |
| 4 | 0 | 2 | 0 | 3 | 1.25 | 1.50 |
| 5 | 34 | 32 | 32 | 28 | 31.5 | 2.52 |
| 6 | 38 | 36 | 36 | 39 | 37.25 | 1.50 |
| 7 | 29 | 29 | 32 | 29 | 29.75 | 1.50 |
| 8 | 37 | 35 | 36 | 33 | 35.25 | 1.71 |
Videos 1–4 were performed by novice surgeons, 5–8 by competent surgeons. Scores were out of a possible total of 40. Four expert surgeons (A, B, C and D) graded all eight videos independently.