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Comments on: Goodness-of-fit tests in mixed modes: smooth tests of goodness-of-fit for the random effects distribution in linear mixed models Universiteit Gent
An ODE-based mixed modelling approach for B- and T-cell dynamics induced by Varicella-Zoster Virus vaccines in adults shows higher T-cell proliferation with Shingrix than with Varilrix Universiteit Hasselt Vrije Universiteit Brussel Universiteit Antwerpen
Clinical trials covering the immunogenicity of a vaccine aim to study the longitudinal dynamics of certain immune cells after vaccination. The corresponding immunogenicity datasets are mainly analyzed by the use of statistical (mixed effects) models. This paper proposes the use of mathematical ordinary differential equation (ODE) models, combined with a mixed effects approach. ODE models are capable of translating underlying immunological post ...
A mixed effects least squares support vector machine model for classification of longitudinal data Universiteit Hasselt KU Leuven
A mixed effects least squares support vector machine (LS-SVM) classifier is introduced to extend the standard LS-SVM classifier for handling longitudinal data. The mixed effects LS-SVM model contains a random intercept and allows to classify highly unbalanced data, in the sense that there is an unequal number of observations for each case at non-fixed time points. The methodology consists of a regression modeling and a classification step based ...
Application of Semiparametric Mixed Models and Simultaneous Confidence Bands in a Cardiovascular Safety Experiment with Longitudinal Data Universiteit Hasselt KU Leuven
Several pharmacological studies involve experiments aimed at testing for a difference between experimental groups wherein the data are longitudinal in nature, frequently with long sequences per subject. Oftentimes, treatment effect, if present, is not constant over time. In such situations, imposing a parametric mean structure can be too complicated and/or restrictive. A more flexible approach is to model the mean using a semiparametric smooth ...
Genetic algorithm for a delivery problem with mixed time windows Universiteit Hasselt
This research aims to improve transportation planning decisions for a production company, which produces seasoning powder in Thailand and the logistics provider. Due to restrictions in Bangkok and its metropolitan area, the routing problem becomes one with two types of time windows. A mixed integer programming model is formulated, which aims to minimize a cost function which consists of fixed vehicle costs, variable vehicle costs and fuel costs. ...
A family of tests to detect misspecifications in the random-effects structure of generalized linear mixed models Universiteit Hasselt KU Leuven
Estimation in generalized linear mixed models for non-Gaussian longitudinal data is often based on maximum likelihood theory, which assumes that the underlying probability model is correctly specified. It is known that the results obtained from these models are not always robust against misspecification of the random-effects structure. Therefore, diagnostic tools for the detection of this misspecification are of the utmost importance. Three ...
Modeling the effect of distance from a hydro-electric dam on malaria incidence based on frailty and mixed Poisson regression models Universiteit Gent
The research presented in this thesis is motivated by the question whether hydro-electric dams have an impact on malaria incidence. The specific problem that arises in the malaria data is the confounding of the clustering, village, with the covariate of interest, distance from the dam. The effect of this confounding problem is investigated in the multivariate survival data. In Chapter 1, the burden and epidemiology of malaria is put into context ...
Assessment of livestock feed resources and coping strategies with dry season feed scarcity in mixed crop-livestock farming systems around the Gilgel Gibe catchment, Southwest Ethiopia Universiteit Gent
In the current study area, livestock are an integral part of the mixed farming system, and play very important roles as sources of draught power, nutrition, cash income, employment and poverty alleviation. However, feed shortage, especially during the dry season, is the most important constraint to optimal productivity. This study aimed to investigate livestock feed resources and feeding practices, coping strategies with seasonal scarcity, and ...
Estimating negative variance components from Gaussian and non-Gaussian data: A mixed models approach Universiteit Hasselt KU Leuven
The occurrence of negative variance components is a reasonably well understood phenomenon in the case of linear models for hierarchical data, such as variance-component models in designed experiments or linear mixed models for longitudinal data. In many cases, such negative variance components can be translated as negative within-unit correlations. It is shown that negative variance components, with corresponding negative associations, can occur ...