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Developing sound or reliable statistical models for analyzing vehicle crashes is veryimportant in highway safety studies. A difficulty arises when crash data exhibit overdispersion.Over-dispersion caused by unobserved heterogeneity is a serious problemand has been addressed in a variety ways...
Persistent link: https://www.econbiz.de/10009464902
In this thesis, we propose to analyze panel count data using a spline-basedsieve generalized estimating equation method with a semiparametric proportional mean model E(N(t)|Z) = Λ0(t) eβT0Z. The natural log of the baseline mean function, logΛ0(t), is approximated by a monotone cubic B-spline...
Persistent link: https://www.econbiz.de/10009466051
Statistical modeling of traffic crashes has been of interest to researchers for decades. Over the most recent decade many crash models have accounted for extra-variation in crash counts?variation over and above that accounted for by the Poisson density. The extra-variation ? or dispersion ? is...
Persistent link: https://www.econbiz.de/10009483403
model assumptions. Individual-level residuals are easy to estimate in the Bayesian SEM and are used to dene posterior … predictive checks for model assumptions. The empirical cumulative distribution function of the residuals is used to test the … assumption that the residual error is normally distributed. Cumulative sums of the residuals are used to check the assumption …
Persistent link: https://www.econbiz.de/10009483015