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Article
Bayesian sequential designs in studies with multilevel data
In many studies in the social and behavioral sciences, the data have a multilevel structure, with subjects nested within clusters. In the design phase of such a study, the number of clusters to achieve a desir...
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Article
Open AccessPower analysis of longitudinal studies with piecewise linear growth and attrition
In longitudinal research, the development of some outcome variable(s) over time (or age) is studied. Such relations are not necessarily smooth, and piecewise growth models may be used to account for differenti...
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Article
Open AccessThe relation between creativity and students’ performance on different types of geometrical problems in elementary education
In the current study we aimed to investigate the relation between creativity and mathematical problem solving in the upper grades of elementary school.
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Article
Open AccessThe effect of missing data on design efficiency in repeated cross-sectional multi-period two-arm parallel cluster randomized trials
The reduced efficiency of the cluster randomized trial design may be compensated by implementing a multi-period design. The trial then becomes longitudinal, with a risk of intermittently missing observations a...
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Article
Open AccessBayesian updating: increasing sample size during the course of a study
A priori sample size calculation requires an a priori estimate of the size of the effect. An incorrect estimate may result in a sample size that is too low to detect effects or that is unnecessarily high. An a...
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Article
Open AccessSample-size determination for the Bayesian t test and Welch’s test using the approximate adjusted fractional Bayes factor
When two independent means μ1 and μ2 are compared, H0 : μ1 = μ2, H1 : μ1≠μ2, and H2 : μ1 > μ2 are the hypotheses of interest. This paper introduces the R package SSDbain, which can be used to determine the sample...
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Article
Open AccessThe process of early self-control: an observational study in two- and three-year-olds
Early individual differences in self-control are predictive of numerous developmental outcomes, such as physical health and risk-taking behaviours. Therefore, it is important to improve our understanding of ho...
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Article
Open AccessDismantling the relative effectiveness of core components of cognitive behavioural therapy in preventing depression in adolescents: protocol of a cluster randomized microtrial
Both depressive disorder and subclinical depressive symptoms during adolescence are a major public health concern. Therefore, it is important that depression is detected at an early stage and is treated preven...
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Article
Open AccessBayesian evaluation of informative hypotheses in cluster-randomized trials
Researchers often have informative hypotheses in mind when comparing means across treatment groups, such as H1 : μA < μB < μC and H2 : μB < μA < μC, and want to compare these hypotheses to each other directly. Th...
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Article
Open AccessHow large are the consequences of covariate imbalance in cluster randomized trials: a simulation study with a continuous outcome and a binary covariate at the cluster level
The number of clusters in a cluster randomized trial is often low. It is therefore likely random assignment of clusters to treatment conditions results in covariate imbalance. There are no studies that quantif...
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Article
Open AccessRobustness of parameter and standard error estimates against ignoring a contextual effect of a subject-level covariate in cluster-randomized trials
In experimental research, it is not uncommon to assign clusters to conditions. When analysing the data of such cluster-randomized trials, a multilevel analysis should be applied in order to take into account t...
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Chapter
Optimal Designs for Multilevel Studies
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Reference Work Entry In depth
Cluster Randomized Trials: Design and Analysis
The first section of this chapter gives an introduction to cluster randomized trials, and the reasons why such trials are often chosen above simple randomized trials. It also argues that more ad...
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Article
A Comparison of Estimation Methods for Multilevel Logistic Models
In this paper a comparison between Penalized Quasi Likelihood (PQL) and estimation by numerical integration is made for the analysis of two-level experimental binary data with two treatment conditions. The com...
