Logistic regression analysis for accidents in the previous year
| Variable | B | Wald score | p value | Odds ratio | Lower 95% CI | Upper 95% CI |
| Off-road events/h | 0.004 | 3.37 | <0.03 | 1.004 | 1.0004 | 1.008 |
| Tracking error | 0.09 | 0.03 | >0.05 | 1.1 | 0.79 | 1.53 |
| Reaction time | 0.1 | 0.5 | >0.05 | 1.1 | 0.83 | 1.5 |
| Epworth score | 0.08 | 2.02 | >0.05 | 1.09 | 0.97 | 1.22 |
| RDI | 0.006 | 0.26 | >0.05 | 1.006 | 0.98 | 1.03 |
RDI = respiratory disturbance index.
4-150 OR for every 1 unit increase in variable (i.e. estimated risk of road traffic accident increases by 1.004 or 0.4% for every additional off-road event on the simulator).