Table 3.
Model results including the marginal effects.
| Variables | In Injury severity of: | Parameter estimates: | t-statistics | Marginal Effects |
||
|---|---|---|---|---|---|---|
| Major Injury | Minor Injury | No Injury | ||||
| Constant | 1.47 | 17.91 | ||||
| Random Parameter | ||||||
| Shoulder and Lap Belt Used | Major Injury | −3.01 | −3.75 | −0.0066 | 0.0009 | 0.0057 |
| Standard deviation “Shoulder and Lap Belt Used” (Normally distributed) | 1.94 | 3.24 | ||||
| Male driver | Minor Injury | −1.13 | −5.29 | −0.0006 | 0.011 | −0.0104 |
| Standard deviation “Male” (Normally distributed) | 1.99 | 6.83 | ||||
| Overturn/Rollover | Minor Injury | 0.69 | 2.19 | −0.0014 | 0.012 | −0.0106 |
| Standard deviation “Overturn/Rollover” (Normally distributed) | 2.66 | 2.9 | ||||
| Heterogeneity in means | ||||||
| Shoulder and Lap Belt Used: Tire blowout or separation | 0.56 | 3.57 | ||||
| Male driver: Tire blowout or separation | −0.34 | −2.81 | ||||
| Overturn/Rollover: Tire blowout or separation | 0.54 | 1.84 | ||||
| Crash characteristics | ||||||
| DUI | Major Injury | 0.61 | 2.46 | 0.0008 | −0.0001 | −0.0006 |
| Head on crash | Major Injury | 0.79 | 3.21 | 0.001 | −0.0002 | −0.0008 |
| No shoulder and lap belt used | Major Injury | 0.78 | 6.22 | 0.0056 | −0.0011 | −0.0045 |
| Airbag deployed | Minor Injury | 1.27 | 14.22 | −0.0011 | 0.0177 | −0.0166 |
| Collision with a ditch (First harmful event) | No Injury | −0.38 | −3.38 | 0.0007 | 0.0021 | −0.0029 |
| Driving too Fast for Conditions | No Injury | −0.35 | −3.73 | 0.001 | 0.003 | −0.0039 |
| Rear end collision | No Injury | 0.36 | 5.61 | −0.0039 | −0.0108 | 0.0127 |
| Driver Characteristics | ||||||
| Teenage driver (13–19 years) | Minor Injury | 0.48 | 4.86 | −0.0004 | 0.0086 | −0.0081 |
| Driver Age (20–39 years) | Minor Injury | 0.45 | 5.74 | −0.0015 | 0.0275 | −0.026 |
| Employed | No Injury | 0.39 | 7.86 | −0.006 | −0.0219 | 0.0279 |
| Driver age (40–59 years) | No Injury | −0.25 | −3.17 | 0.0021 | 0.0058 | −0.0079 |
| Road and Environmental Characteristics | ||||||
| Curve Left and Down Grade | Major Injury | 0.70 | 3.32 | 0.0014 | −0.0003 | −0.0011 |
| Rain | Major Injury | −0.60 | −3.94 | −0.003 | 0.0006 | 0.0025 |
| Vehicle Characteristics | ||||||
| Improper Tread Depth (Vehicle defect) | Major Injury | 1.12 | 7.65 | 0.0079 | −0.0015 | −0.0064 |
| Pick up | Major Injury | −0.48 | −3.82 | −0.0032 | 0.0005 | 0.0027 |
| Brake (Vehicle defect) | Minor Injury | 0.43 | 6.79 | −0.0009 | 0.0229 | −0.022 |
| Component failure (first harmful event) | Minor Injury | −0.46 | −4.18 | 0.0002 | −0.0041 | 0.0039 |
| Passenger car | No Injury | 0.21 | 4.09 | −0.0027 | −0.0109 | 0.0136 |
| Wheels (Vehicle defect) | No Injury | 0.33 | 2.66 | −0.0004 | −0.0016 | 0.002 |
| Headlight (vehicle defect) | No Injury | −1.12 | −4.59 | 0.0005 | 0.0011 | −0.0015 |
| Vehicle age (less than 6 years) | No Injury | 0.39 | 5.26 | −0.0015 | −0.0057 | 0.0072 |
| Vehicle age (6–10 years) | No Injury | 0.26 | 3.99 | −0.0012 | −0.0049 | 0.0061 |
| Model Statistics | ||||||
| Number of Observations | 15054 | |||||
| Log-likelihood at constants | −16538.51 | |||||
| Log-likelihood at convergence | −9396.51 | |||||
| McFadden Pseudo r squared | 0.43 | |||||