Table 4 Multiple regression analysis: rated degree of difficulty
| Predictor variable | b | SE | t | 95% CI | p value |
|---|---|---|---|---|---|
| Time to first successful ventilation | 0.08 | 0.01 | 7.38 | 0.06–0.10 | < 0.001 |
| Attempts required for successful placement | 2.61 | 0.65 | 4.02 | 1.32–3.90 | < 0.001 |
| Constant | − 1.92 | 0.73 | − 2.64 | − 3.37 to − 0.48 | 0.01 |