Table 2 Estimation results for the partial proportional odds model

 Driver characteristics

Male

–

–

n.s.

 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

 Upgrade

–

–

n.s.

 Downgrade

−2.230

0.312

<  0.001

 Environmental conditions

 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

 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

 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

α_1–2

−2.193

0.753

0.004

α_2–3

−11.671

1.315

<  0.001

Fit-of-goodness

Number of observations

Log likelihood at zero

Log likelihood at convergence

Pseudo R²