Comparison between participants’ performance with visual aid usage off or on
| Parameter | Mean (range) | P value | |
| Visual aid off | Visual aid on | ||
| Total number of attempts | 10.9 (6–29) | 8.9 (6–19) | 0.01 |
| Total bone contacts | 4.3 (0–23) | 2.8 (0–14) | 0.02 |
| Total procedure time (s) | 230 (27–605) | 194 (0–1079 | 0.02 |
| Total dura contacts | 0.4 (0–5) | 0.3 (0–2) | 0.07 |
| Total spinal taps | 0.12 (0–4) | 0.04 (0–2) | 0.4 |