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The phenomenon of overdispersion arises when categorical or count data exhibit variability larger than expected … outlined in the GEE methodology. Although this accounts for overdispersion, we will show that these methods tend to provide … account for the overdispersion without overly inflating the standard errors. In particular, we apply this method for …
Persistent link: https://www.econbiz.de/10009439430
Recently gravity trade models are applied to disaggregated trade data. Here manyzeros are characteristic. In the presence of excess zeros usual Poisson Pseudo MaximumLikelihood (PPML) is still consistent, the variance covariance matrix howeveris invalid. Correct economic interpretation however...
Persistent link: https://www.econbiz.de/10009442838
Using estimation of demand for the George Washington/Jefferson NationalForest as a case study, it is shown that in a stratified/clustered on-sitesample, latent heterogeneity needs to be accounted for twice: first to accountfor dispersion in the data caused by unobservability of the process that...
Persistent link: https://www.econbiz.de/10009444348
Predicting abundance across a species' distribution is useful for studies of ecology and biodiversity management. Modeling of survey data in relation to environmental variables can be a powerful method for extrapolating abundances across a species' distribution and, consequently, calculating...
Persistent link: https://www.econbiz.de/10009448803