Random-Parameter Multivariate Negative Binomial Regression for Modeling Impacts of Contributing Factors on the Crash Frequency by Crash Types
Table 1
Descriptive statistics of dependent variables.
Variable names
Definitions
Minimum
Maximum
Mean
SD
Rear-end crash
Rear-end crash occurs when a vehicle strikes the one in front of it
1
27
4.58
3.93
Bumping-guardrail crash
A vehicle strikes the guardrails in the middle of or outside the highways
1
14
3.08
2.23
Other crash
This type includes roll-over (a vehicle tips over onto its side or roof), fire (a vehicle caught fire due to mechanical failure), scrub (crashes caused by side scrub between vehicles), and other crashes
0
14
1.18
1.59
Noncasualty crash
Crashes leading to property damage only
0
42
6.70
6.41
Casualty crash
Crashes resulted in injury, disability, or fatality
