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Table 2 Estimation results for the partial proportional odds model

From: Interpreting risk factors for truck crash severity on mountainous freeways in Jiangxi and Shaanxi, China

Varbiables Definition Est. St.Err p
β1
 Driver characteristics Male n.s.
Age
 Adult (30~50 years) n.s.
 Old (>  50 years) 0.844 0.319 0.008
Failure to wear a seatbelt 1.664 0.266 <  0.001
 Vehicle attibutes Multiple vehicles involved 0.988 0.251 <  0.001
Commercial transport −1.921 0.513 <  0.001
Overloading 2.089 0.240 <  0.001
Brake Failure 0.687 0.274 0.012
Disregarding speed limit 1.436 0.239 <  0.001
Unsafe following distance 1.433 0.236 <  0.001
 Road geometrics Curve 0.619 0.226 0.006
Vertical alignment
 Upgrade n.s.
 Downgrade −2.230 0.312 <  0.001
 Environmental conditions Season
 Summer 1.453 0.320 <  0.001
 Autumn −0.966 0.418 0.021
 Winter 1.596 0.313 <  0.001
Weekday −0.457 0.199 0.022
Nighttime 1.484 0.246 <  0.001
Adverse weather 1.563 0.260 <  0.001
β2
 Driver characteristics Failure to wear a seatbelt −1.177 0.403 0.003
 Vehicle attibutes Multiple vehicles involved −0.911 0.423 0.031
Overloading 1.484 0.734 0.043
Brake Failure −1.139 0.480 0.018
Disregarding speed limit 1.673 0.578 0.004
 Road geometrics Unsafe following distance −1.121 0.518 0.030
 Curve 1.374 0.454 0.002
 Downgrade 1.141 0.441 0.010
 Environmental conditions Season
 Autumn 3.053 0.758 <  0.001
 Winter 1.418 0.464 0.002
Nighttime 0.909 0.427 0.033
Adverse weather 0.915 0.466 0.050
α α1–2 −2.193 0.753 0.004
α2–3 −11.671 1.315 <  0.001
Fit-of-goodness Number of observations   1175
Log likelihood at zero   − 1141.76
Log likelihood at convergence   − 415.37
Pseudo R2   0.636
  1. n.s. Non-significant