A Joint Econometric Approach For Modeling Crash Counts By Collision Type

Keywords

Comparison exercise; Crash types; Equivalent log-likelihood; Joint system; Multinomial fractional split model; Unobserved effect

Abstract

In recent years, there is growing recognition that common unobserved factors that influence crash frequency by one attribute level are also likely to influence crash frequency by other attribute levels. The most common approach employed to address the potential unobserved heterogeneity in safety literature is the development of multivariate crash frequency models. The current study proposes an alternative joint econometric framework to accommodate for the presence of unobserved heterogeneity – referred to as joint negative binomial-multinomial logit fractional split (NB-MNLFS) model. Furthermore, the study undertakes a first of its kind comparison exercise between the most commonly used multivariate model (multivariate random parameter negative binomial model) and the proposed joint approach by generating an equivalent log-likelihood measure. The empirical analysis is based on the zonal level crash count data for different collision types from the state of Florida for the year 2015. The model results highlight the presence of common unobserved effects affecting the two components of the joint model as well as the presence of parameter heterogeneity. The equivalent log-likelihood and goodness of fit measures clearly highlight the comparable performance offered by the proposed joint model relative to the commonly used multivariate approach. Overall, the model interpretations and fit measures clearly highlight the potential complementary role of the proposed approach for crash frequency analyses.

Publication Date

9-1-2018

Publication Title

Analytic Methods in Accident Research

Volume

19

Number of Pages

16-32

Document Type

Article

Personal Identifier

scopus

DOI Link

https://doi.org/10.1016/j.amar.2018.06.001

Socpus ID

85048805199 (Scopus)

Source API URL

https://api.elsevier.com/content/abstract/scopus_id/85048805199

This document is currently not available here.

Share

COinS