Group-based trajectory models areused to investigate population differences in the developmental courses of behaviors or outcomes. This note introduces a new Stata command, traj, for fitting to longitudinal data finite (discrete) mixture models designed to identify clusters of individuals following similar progressions of some behavior or outcome over age or time. Normal, Censored normal, Poiss...

Abstract The dynamics of the wild boar population has become a pressing issue not only for ecological purposes, but also agricultural and livestock production. data related to dispersal distance can have complex structure, including excess zeros right-censored observations, thus being challenging modeling. In this sense, we propose two different zero-inflated-right-censored regression models, a...

Data with bound-inflated responses are common in many areas of application. Often the data are bounded below by a real number (e.g., zero) with a substantial portion of observations at the boundary value. One approach to analyze such data is the general class of left-inflated mixture models. As a competitive alternative to the quasi-Newton BFGS method, we implement in this article the EM algori...

We introduce the generalized zero-inflated allocation scheme of placing n labeled balls into N labeled cells. We study the asymptotic behavior of the number of empty cells when (n,N) belongs to the “right” and “left” domain of attraction. An application to the estimation of characteristics of agreement among a set of raters which independently classify subjects into one of two categories is als...

This paper is concerned with the analysis of zero-inflated count data when time of exposure varies. It proposes a modified zero-inflated count data model where the probability of an extra zero is derived from an underlying duration model with Weibull hazard rate. The new model is compared to the standard Poisson model with logit zero inflation in an application to the effect of treatment with t...

Abstract Smallholder farmers’ preferences for participation in contract farming may take the form of proportional data––whereby farmers only sell some proportions or fractions their output to contractors. We analyze determinants zero (potential corner solution) and amounts milk that through farming, using dairy data from Zambia. Bayesian linear, linear probability, hurdle models are compared wi...