Editorial on special topic ISCB 2015: “Clinical research design, rare diseases, and personalized medicine”
(Source: Biometrical Journal)
Source: Biometrical Journal - July 5, 2017 Category: Biotechnology Authors: Kit Roes Tags: Short Communication Source Type: research
Contents: Biometrical Journal 4'17
(Source: Biometrical Journal)
Source: Biometrical Journal - July 5, 2017 Category: Biotechnology Tags: Contents Source Type: research
Masthead: Biometrical Journal 4'17
(Source: Biometrical Journal)
Source: Biometrical Journal - July 5, 2017 Category: Biotechnology Tags: Masthead Source Type: research
Editorial Board: Biometrical Journal 4'17
(Source: Biometrical Journal)
Source: Biometrical Journal - July 5, 2017 Category: Biotechnology Tags: Editorial Board Source Type: research
Cover Picture: Biometrical Journal 4'17
(Source: Biometrical Journal)
Source: Biometrical Journal - July 5, 2017 Category: Biotechnology Tags: Cover Picture Source Type: research
A comparison of group prediction approaches in longitudinal discriminant analysis
We describe three approaches to calculating a patient's posterior group membership probabilities which have been outlined in previous studies, based on the marginal distribution of the longitudinal markers, conditional distribution and distribution of the random effects. Here we compare the three approaches, first using data from the Mayo Primary Biliary Cirrhosis study and then by way of simulation study to explore in which situations each of the three approaches is expected to give the best prediction. We demonstrate situations in which the marginal or random‐effects approach perform well, but find that the conditional...
Source: Biometrical Journal - July 1, 2017 Category: Biotechnology Authors: David M. Hughes, Riham El Saeiti, Marta Garc ía‐Fiñana Tags: RESEARCH PAPER Source Type: research
Bayesian joint modeling of bivariate longitudinal and competing risks data: An application to study patient ‐ventilator asynchronies in critical care patients
Mechanical ventilation is a common procedure of life support in intensive care. Patient‐ventilator asynchronies (PVAs) occur when the timing of the ventilator cycle is not simultaneous with the timing of the patient respiratory cycle. The association between severity markers and the events death or alive discharge has been acknowledged before, however, little is known about the addition of PVAs data to the analyses. We used an index of asynchronies (AI) to measure PVAs and the SOFA (sequential organ failure assessment) score to assess overall severity. To investigate the added value of including the AI, we propose a Baye...
Source: Biometrical Journal - July 1, 2017 Category: Biotechnology Authors: Montserrat Ru é, Eleni‐Rosalina Andrinopoulou, Danilo Alvares, Carmen Armero, Anabel Forte, Lluis Blanch Tags: Research Paper Source Type: research
Flexible Bayesian additive joint models with an application to type 1 diabetes research
The joint modeling of longitudinal and time‐to‐event data is an important tool of growing popularity to gain insights into the association between a biomarker and an event process. We develop a general framework of flexible additive joint models that allows the specification of a variety of effects, such as smooth nonlinear, time‐varying and random effects, in the longitudinal and survival parts of the models. Our extensions are motivated by the investigation of the relationship between fluctuating disease‐specific markers, in this case autoantibodies, and the progression to the autoimmune disease type 1 diabetes. ...
Source: Biometrical Journal - July 1, 2017 Category: Biotechnology Authors: Meike K öhler, Nikolaus Umlauf, Andreas Beyerlein, Christiane Winkler, Anette‐Gabriele Ziegler, Sonja Greven Tags: Research Paper Source Type: research
Random walk designs for selecting pool sizes in group testing estimation with small samples
Group testing estimation, which utilizes pooled rather than individual units for testing, has been an ongoing area of research for over six decades. While it is often argued that such methods can yield large savings in terms of resources and/or time, these benefits depend very much on the initial choice of pool sizes. In fact, when poor group sizes are used, the results can be much worse than those obtained using standard techniques. Tools for addressing this problem in the literature have been based on either large sample results or prior knowledge of the parameter being estimated, with little guidance when these assumpti...
Source: Biometrical Journal - July 1, 2017 Category: Biotechnology Authors: Gregory Haber, Yaakov Malinovsky Tags: Research Paper Source Type: research
Prediction accuracy and variable selection for penalized cause ‐specific hazards models
We consider modeling competing risks data in high dimensions using a penalized cause‐specific hazards (CSHs) approach. CSHs have conceptual advantages that are useful for analyzing molecular data. First, working on hazards level can further understanding of the underlying biological mechanisms that drive transition hazards. Second, CSH models can be used to extend the multistate framework for high‐dimensional data. The CSH approach is implemented by fitting separate proportional hazards models for each event type (iCS). In the high‐dimensional setting, this might seem too complex and possibly prone to overfitting. Th...
Source: Biometrical Journal - July 1, 2017 Category: Biotechnology Authors: Maral Saadati, Jan Beyersmann, Annette Kopp ‐Schneider, Axel Benner Tags: RESEARCH PAPER Source Type: research
Decision ‐theoretic designs for a series of trials with correlated treatment effects using the Sarmanov multivariate beta‐binomial distribution
Abstract
The motivation for the work in this article is the setting in which a number of treatments are available for evaluation in phase II clinical trials and where it may be infeasible to try them concurrently because the intended population is small. This paper introduces an extension of previous work on decision‐theoretic designs for a series of phase II trials. The program encompasses a series of sequential phase II trials with interim decision making and a single two‐arm phase III trial. The design is based on a hybrid approach where the final analysis of the phase III data is based on a classical frequentist hy...
Source: Biometrical Journal - July 1, 2017 Category: Biotechnology Authors: Siew Wan Hee, Nicholas Parsons, Nigel Stallard Tags: RESEARCH PAPER Source Type: research
Characterizing cross ‐subject spatial interaction patterns in functional magnetic resonance imaging studies: A two‐stage point‐process model
We develop a two‐stage spatial point process model that introduces new characterizations of activation patterns in multisubject functional Magnetic Resonance Imaging (fMRI) studies. Conventionally multisubject fMRI methods rely on combining information across subjects one voxel at a time in order to identify locations of peak activation in the brain. The two‐stage model that we develop here addresses shortcomings of standard methods by explicitly modeling the spatial structure of functional signals and recognizing that corresponding cross‐subject functional signals can be spatially misaligned. In our first stage anal...
Source: Biometrical Journal - July 1, 2017 Category: Biotechnology Authors: Ad él Lee, Aila Särkkä, Tara M. Madhyastha, Thomas J. Grabowski Tags: Research Paper Source Type: research
Multilevel covariance regression with correlated random effects in the mean and variance structure
Multivariate regression methods generally assume a constant covariance matrix for the observations. In case a heteroscedastic model is needed, the parametric and nonparametric covariance regression approaches can be restrictive in the literature. We propose a multilevel regression model for the mean and covariance structure, including random intercepts in both components and allowing for correlation between them. The implied conditional covariance function can be different across clusters as a result of the random effect in the variance structure. In addition, allowing for correlation between the random intercepts in the m...
Source: Biometrical Journal - July 1, 2017 Category: Biotechnology Authors: Adrian Quintero, Emmanuel Lesaffre Tags: RESEARCH PAPER Source Type: research
Author response to the contributors to the discussion on “A critical evaluation of the current ‘p‐value controversy’”
(Source: Biometrical Journal)
Source: Biometrical Journal - June 29, 2017 Category: Biotechnology Authors: Stefan Wellek Tags: Short Communication Source Type: research
Contribution to the discussion of “A critical evaluation of the current ‘p‐value controversy”'
(Source: Biometrical Journal)
Source: Biometrical Journal - May 26, 2017 Category: Biotechnology Authors: Fulvio Santis Tags: Short Communication Source Type: research
