| Explanatory variables | Parameter | t-stat | |
| Constant | −0.796 | −10.200 | |
| Primary contributing factors | Followed too Close | −0.245 | −2.692 |
| Crash manner | Rear-End (front to rear) | 1.202 | 1.678 |
| Mu (1) | 0.406 | ||
| Mu (2) | 0.811 | ||
| Mu (3) | 1.951 | ||
| Log-likelihood of constant only | −248.701 | ||
| Log-likelihood at convergence | −247.018 | ||