Citation

Francis RA, Geedipally SR, Guikema SD, Dhavala SS, Lord D, Larocca S. Risk Anal. 2012; 32(1): 167-183.

Affiliation

Department of Engineering Management and Systems Engineering, George Washington University, Washington, DC, USA. Department of Geography and Environmental Engineering, Johns Hopkins University, Baltimore, MD, USA. Texas Transportation Institute, Texas A&M University, College Station, TX, USA. Zachry Department of Civil Engineering, Texas A&M University, College Station, TX, USA. Department of Statistics, Texas A&M University, College Station, TX, USA.

Copyright

(Copyright © 2012, Society for Risk Analysis, Publisher John Wiley and Sons)

DOI

10.1111/j.1539-6924.2011.01659.x

PMID

21801191

Abstract

Count data are pervasive in many areas of risk analysis; deaths, adverse health outcomes, infrastructure system failures, and traffic accidents are all recorded as count events, for example. Risk analysts often wish to estimate the probability distribution for the number of discrete events as part of doing a risk assessment. Traditional count data regression models of the type often used in risk assessment for this problem suffer from limitations due to the assumed variance structure. A more flexible model based on the Conway-Maxwell Poisson (COM-Poisson) distribution was recently proposed, a model that has the potential to overcome the limitations of the traditional model. However, the statistical performance of this new model has not yet been fully characterized. This article assesses the performance of a maximum likelihood estimation method for fitting the COM-Poisson generalized linear model (GLM). The objectives of this article are to (1) characterize the parameter estimation accuracy of the MLE implementation of the COM-Poisson GLM, and (2) estimate the prediction accuracy of the COM-Poisson GLM using simulated data sets. The results of the study indicate that the COM-Poisson GLM is flexible enough to model under-, equi-, and over-dispersed data sets with different sample mean values. The results also show that the COM-Poisson GLM yields accurate parameter estimates. The COM-Poisson GLM provides a promising and flexible approach for performing count data regression.

Language: en