Bayesian hierarchical analysis of within-units variances in repeated measures experiments

1994 ◽  
Vol 13 (18) ◽  
pp. 1841-1852 ◽  
Author(s):  
Thomas R. Ten Have ◽  
Vernon M. Chinchilli
2020 ◽  
Author(s):  
Zsolt Turi ◽  
Matthias Mittner ◽  
Albert Lehr ◽  
Hannah Bürger ◽  
Andrea Antal ◽  
...  

Cognitive control is a hypothetical mental process, which underlies adaptive goal-directed decisions. Previous studies have linked cognitive control to electrophysiological fluctuations in the theta band and theta-gamma cross-frequency coupling (CFC) arising from the cingulate and frontal cortices. Yet, to date the behavioral consequences of different forms of theta-gamma CFC remain elusive. Here, we studied the behavioral effects of the theta-gamma CFC via transcranial alternating current stimulation (tACS) designed to stimulate the frontal and cingulate cortices. Using a double-blind, randomized, repeated measures study design, 24 healthy participants were subjected to three main, active CFC-tACS protocols: Short gamma frequency bursts (80 Hz) were coupled to an ongoing theta cycle (4 Hz) to coincide with either the peaks or the troughs of the theta wave. In a third condition, the amplitude of the gamma oscillation was modulated by the phase of a theta cycle. In the fourth, control protocol, gamma was continuously superimposed over the theta cycle, therefore lacking any phase-specificity in the CFC. During the 20-minute stimulations, the participants performed a Go/NoGo monetary reward- and punishment-based instrumental learning task. A Bayesian hierarchical logistic regression analysis revealed that CFC-tACS over peak had no effects on the behavioral performance, whereas CFC-tACS over trough and, to a lesser extent, amplitude-modulated tACS reduced performance in conflicting trials. Our results suggest that cognitive control depends on the phase-specificity of the theta-gamma CFC.


2019 ◽  
Vol 11 (1) ◽  
pp. 57-91 ◽  
Author(s):  
Rachael Meager

Despite evidence from multiple randomized evaluations of microcredit, questions about external validity have impeded consensus on the results. I jointly estimate the average effect and the heterogeneity in effects across seven studies using Bayesian hierarchical models. I  find the impact on household business and consumption variables is unlikely to be transformative and may be negligible. I find reasonable external validity: true heterogeneity in effects is moderate, and approximately 60 percent of observed heterogeneity is sampling variation. Households with previous business experience have larger but more heterogeneous effects. Economic features of microcredit interventions predict variation in effects better than studies’ evaluation protocols. (JEL D14, G21, I38, O12, O16, P34, P36)


2020 ◽  
Vol 21 (1) ◽  
Author(s):  
Brian E. Vestal ◽  
Camille M. Moore ◽  
Elizabeth Wynn ◽  
Laura Saba ◽  
Tasha Fingerlin ◽  
...  

2010 ◽  
Vol 15 (3) ◽  
pp. 290-307 ◽  
Author(s):  
Taeryon Choi ◽  
Mark J. Schervish ◽  
Ketra A. Schmitt ◽  
Mitchell J. Small

2012 ◽  
Vol 3 ◽  
Author(s):  
Oliver Dyjas ◽  
Raoul P. P. P. Grasman ◽  
Ruud Wetzels ◽  
Han L. J. van der Maas ◽  
Eric-Jan Wagenmakers

2017 ◽  
Author(s):  
Rachael Meager

This paper develops methods to aggregate evidence on distributional treatment effects from multiple studies conducted in different settings, and applies them to the microcredit literature. Several randomized trials of expanding access to microcredit found substantial effects on the tails of household outcome distributions, but the extent to which these findings generalize to future settings was not known. Aggregating the evidence on sets of quantile effects poses additional challenges relative to average effects because distributional effects must imply monotonic quantiles and pass information across quantiles. Using a Bayesian hierarchical framework, I develop new models to aggregate distributional effects and assess their generalizability. For continuous outcome variables, the methodological challenges are addressed by applying transforms to the unknown parameters. For partially discrete variables such as business profits, I use contextual economic knowledge to build tailored parametric aggregation models. I find generalizable evidence that microcredit has negligible impact on the distribution of various household outcomes below the 75th percentile, but above this point there is no generalizable prediction.


2008 ◽  
Vol 42 (15) ◽  
pp. 5607-5614 ◽  
Author(s):  
Thomas J. Santner ◽  
Peter F. Craigmile ◽  
Catherine A. Calder ◽  
Rajib Paul

Author(s):  
Christopher McMahan ◽  
James Baurley ◽  
William Bridges ◽  
Chase Joyner ◽  
Muhamad Fitra Kacamarga ◽  
...  

AbstractGenomic studies of plants often seek to identify genetic factors associated with desirable traits. The process of evaluating genetic markers one by one (i.e. a marginal analysis) may not identify important polygenic and environmental effects. Further, confounding due to growing conditions/factors and genetic similarities among plant varieties may influence conclusions. When developing new plant varieties to optimize yield or thrive in future adverse conditions (e.g. flood, drought), scientists seek a complete understanding of how the factors influence desirable traits. Motivated by a study design that measures rice yield across different seasons, fields, and plant varieties in Indonesia, we develop a regression method that identifies significant genomic factors, while simultaneously controlling for field factors and genetic similarities in the plant varieties. Our approach develops a Bayesian maximum a posteriori probability (MAP) estimator under a generalized double Pareto shrinkage prior. Through a hierarchical representation of the proposed model, a novel and computationally efficient expectation-maximization (EM) algorithm is developed for variable selection and estimation. The performance of the proposed approach is demonstrated through simulation and is used to analyze rice yields from a pilot study conducted by the Indonesian Center for Rice Research.


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