A beta ‐binomial mixed‐effects model approach for analysing longitudinal discrete and bounded outcomes
AbstractPatient ‐reported outcomes (PROs) are currently being increasingly used as primary outcome measures in observational and experimental studies since they inform clinicians and researchers about the health‐status of patients and generate data to facilitate improved care. PROs usually appear as discrete an d bounded with U, J, or inverse J shapes, and hence, exponential family members offer inadequate distributional fits. The beta‐binomial distribution has been proposed in the literature to fit PROs. However, the fact that the beta‐binomial distribution does not belong to the exponential family li mits its app...
Source: Biometrical Journal - November 27, 2018 Category: Biotechnology Authors: Josu Najera ‐Zuloaga,
Dae‐Jin Lee,
Inmaculada Arostegui Tags: RESEARCH PAPER Source Type: research
Penalized likelihood and multiple testing
AbstractThe classical multiple testing model remains an important practical area of statistics with new approaches still being developed. In this paper we develop a new multiple testing procedure inspired by a method sometimes used in a problem with a different focus. Namely, the inference after model selection problem. We note that solutions to that problem are often accomplished by making use of a penalized likelihood function. A classic example is the Bayesian information criterion (BIC) method. In this paper we construct a generalized BIC method and evaluate its properties as a multiple testing procedure. The procedure...
Source: Biometrical Journal - November 26, 2018 Category: Biotechnology Authors: Arthur Cohen,
John Kolassa,
Harold B. Sackrowitz Tags: RESEARCH PAPER Source Type: research
A Bayesian joint model of recurrent events and a terminal event
AbstractRecurrent events could be stopped by a terminal event, which commonly occurs in biomedical and clinical studies. In this situation, dependent censoring is encountered because of potential dependence between these two event processes, leading to invalid inference if analyzing recurrent events alone. The joint frailty model is one of the widely used approaches to jointly model these two processes by sharing the same frailty term. One important assumption is that recurrent and terminal event processes are conditionally independent given the subject ‐level frailty; however, this could be violated when the dependency ...
Source: Biometrical Journal - November 26, 2018 Category: Biotechnology Authors: Zheng Li,
Vernon M. Chinchilli,
Ming Wang Tags: RESEARCH PAPER Source Type: research
Adjusting for selection bias in assessing treatment effect estimates from multiple subgroups
AbstractThis paper discusses a number of methods for adjusting treatment effect estimates in clinical trials where differential effects in several subpopulations are suspected. In such situations, the estimates from the most extreme subpopulation are often overinterpreted. The paper focusses on the construction of simultaneous confidence intervals intended to provide a more realistic assessment regarding the uncertainty around these extreme results. The methods from simultaneous inference are compared with shrinkage estimates arising from Bayesian hierarchical models by discussing salient features of both approaches in a t...
Source: Biometrical Journal - November 25, 2018 Category: Biotechnology Authors: Ekkehard Glimm Tags: RESEARCH PAPER Source Type: research
Confidence regions for treatment effects in subgroups in biomarker stratified designs
AbstractSubgroup analysis has important applications in the analysis of controlled clinical trials. Sometimes the result of the overall group fails to demonstrate that the new treatment is better than the control therapy, but for a subgroup of patients, the treatment benefit may exist; or sometimes, the new treatment is better for the overall group but not for a subgroup. Hence we are interested in constructing a simultaneous confidence interval for the difference of the treatment effects in a subgroup and the overall group. Subgroups are usually formed on the basis of a predictive biomarker such as age, sex, or some genet...
Source: Biometrical Journal - November 25, 2018 Category: Biotechnology Authors: Fang Wan,
Cornelia U. Kunz,
Thomas F. Jaki Tags: RESEARCH PAPER Source Type: research
Semiparametric transformation models for interval ‐censored data in the presence of a cure fraction
AbstractMixed case interval ‐censored data arise when the event of interest is known only to occur within an interval induced by a sequence of random examination times. Such data are commonly encountered in disease research with longitudinal follow‐up. Furthermore, the medical treatment has progressed over the last decade with an increasing proportion of patients being cured for many types of diseases. Thus, interest has grown in cure models for survival data which hypothesize a certain proportion of subjects in the population are not expected to experience the events of interest. In this article, we consider a two‐ ...
Source: Biometrical Journal - November 25, 2018 Category: Biotechnology Authors: Chyong ‐Mei Chen,
Pao‐sheng Shen,
Wei‐Lun Huang Tags: RESEARCH PAPER Source Type: research
Estimation in the progressive illness ‐death model: A nonexhaustive review
AbstractMultistate models can be successfully used for describing complex event history data, for example, describing stages in the disease progression of a patient. The so ‐called “illness‐death” model plays a central role in the theory and practice of these models. Many time‐to‐event datasets from medical studies with multiple end points can be reduced to this generic structure. In these models one important goal is the modeling of transition rates but bi omedical researchers are also interested in reporting interpretable results in a simple and summarized manner. These include estimates of predictive probabi...
Source: Biometrical Journal - November 20, 2018 Category: Biotechnology Authors: Lu ís Meira‐Machado,
Marta Sestelo Tags: RESEARCH PAPER Source Type: research
A note on tests for relevant differences with extremely large sample sizes
AbstractA well ‐known problem in classical two‐tailed hypothesis testing is thatP‐values go to zero when the sample size goes to infinity, irrespectively of the effect size. This pitfall can make the testing of data consisting of large sample sizes potentially unreliable. In this note, we propose to test for relevant differences to overcome this issue. We illustrate the propos ed test a on real data set of about 40 million privately insured patients. (Source: Biometrical Journal)
Source: Biometrical Journal - November 11, 2018 Category: Biotechnology Authors: Andrea Callegaro,
Cheikh Ndour,
Emmanuel Aris,
Catherine Legrand Tags: SHORT COMMUNICATION Source Type: research
Optimal promising zone designs
AbstractClinical trials with adaptive sample size reassessment based on an unblinded analysis of interim results are perhaps the most popular class of adaptive designs (see Els äßer et al., 2007). Such trials are typically designed by prespecifying a zone for the interim test statistic, termed the promising zone, along with a decision rule for increasing the sample size within that zone. Mehta and Pocock (2011) provided some examples of promising zone designs and discus sed several procedures for controlling their type‐1 error. They did not, however, address how to choose the promising zone or the corresponding sample...
Source: Biometrical Journal - November 8, 2018 Category: Biotechnology Authors: Samuel T. Hsiao,
Lingyun Liu,
Cyrus R. Mehta Tags: RESEARCH PAPER Source Type: research
Construction of confidence intervals for the maximum of the Youden index and the corresponding cutoff point of a continuous biomarker
AbstractEvaluation of the overall accuracy of biomarkers might be based on average measures of the sensitivity for all possible specificities ‐and vice versa‐ or equivalently the area under the receiver operating characteristic (ROC) curve that is typically used in such settings. In practice clinicians are in need of a cutoff point to determine whether intervention is required after establishing the utility of a continuous biomarker. The Youden index can serve both purposes as an overall index of a biomarker's accuracy, that also corresponds to an optimal, in terms of maximizing the Youden index, cutoff point that in t...
Source: Biometrical Journal - November 8, 2018 Category: Biotechnology Authors: Leonidas E. Bantis,
Christos T. Nakas,
Benjamin Reiser Tags: RESEARCH PAPER Source Type: research
A Bayesian decision analysis approach to assess voice disorder risks by using acoustic features
AbstractVocal fold nodules are recognized as an occupational disease for all collective of workers performing activities for which maintained and continued use of voice is required. Computer ‐aided systems based on features extracted from voice recordings have been considered as potential noninvasive and low cost tools to diagnose some voice‐related diseases. A Bayesian decision analysis approach has been proposed to classify university lectures in three levels of risk: low, medium, and high, based on the information provided by acoustic features extracted from healthy controls and people suffering from vocal fold nodu...
Source: Biometrical Journal - November 8, 2018 Category: Biotechnology Authors: Mar ía J. Rufo,
Jacinto Martín,
Carlos J. Pérez,
Sandra Paniagua Tags: RESEARCH PAPER Source Type: research
Cover Picture: Biometrical Journal 6'18
Biometrical Journal,Volume 60, Issue 6, November 2018. (Source: Biometrical Journal)
Source: Biometrical Journal - November 5, 2018 Category: Biotechnology Source Type: research
Contents: Biometrical Journal 6'18
Biometrical Journal,Volume 60, Issue 6, November 2018. (Source: Biometrical Journal)
Source: Biometrical Journal - November 5, 2018 Category: Biotechnology Source Type: research
Masthead: Biometrical Journal 6'18
Biometrical Journal,Volume 60, Issue 6, November 2018. (Source: Biometrical Journal)
Source: Biometrical Journal - November 5, 2018 Category: Biotechnology Source Type: research
Editorial Board: Biometrical Journal 6'18
Biometrical Journal,Volume 60, Issue 6, November 2018. (Source: Biometrical Journal)
Source: Biometrical Journal - November 5, 2018 Category: Biotechnology Source Type: research
