Multivariate injury severity models that consider the cross-group heterogeneity in the crash
data where individuals or occupants are nested within vehicles and vehicles are nested
within crashes are limited in the literature. Most previous studies on crash injury severity
were conducted at the crash level ignoring the potential correlation in severity for the
vehicles involved in the same crashes or individuals involved in the same vehicles. Ignoring
these correlation and dependence effects might result in underestimation of standard errors …