I am trying to build random parameters model with heterogeneity in mean and variance (RPNB-HMV) models for road traffic crashes on a highway in India.
Random parameter Negative Binomial models are the most popular models for assessing unobserved heterogeneity in crash prediction models.
I want to know some free or open-source software like R for fitting such models.
E.g. A sample syntax of the RPNB-HMV model in R software.