14.02.2013 | Danping Liu, Xiao‐Hua Zhou, Biometrics, 2013

Summary In ROC analysis, covariate adjustment is advocated when the covariates impact the magnitude or accuracy of the test under study. Meanwhile, for many large scale screening tests, the true condition status may be subject to missingness because it is expensive and/or invasive to ...

mehr

05.02.2013 | Rebecca A. Hubbard, Diana L. Miglioretti, Biometrics, 2013

Summary False‐positive test results are among the most common harms of screening tests and may lead to more invasive and expensive diagnostic testing procedures. Estimating the cumulative risk of a false‐positive screening test result after repeat screening rounds is, therefore, important ...

mehr

05.02.2013 | L. Altstein, G. Li, Biometrics, 2013

Summary This article studies a semiparametric accelerated failure time mixture model for estimation of a biological treatment effect on a latent subgroup of interest with a time‐to‐event outcome in randomized clinical trials. Latency is induced because membership is observable in one arm of ...

mehr

05.02.2013 | Rena Jie Sun, John D. Kalbfleisch, Biometrics, 2013

Summary In order to monitor a medical center’s survival outcomes using simple plots, we introduce a risk‐adjusted Observed–Expected (O–E) Cumulative SUM (CUSUM) along with monitoring bands as decision criterion.The proposed monitoring bands can be used in place of a more traditional but ...

mehr

05.02.2013 | Paul R. Rosenbaum, Biometrics, 2013

Summary.  In an observational study, one treated subject may be matched for observed covariates to either one or several untreated controls. The common motivation for using several controls rather than one is to increase the power of a test of no effect under the doubtful assumption that ...

mehr

05.02.2013 | Tim Bancroft, Chuanlong Du, Dan Nettleton, Biometrics, 2013

Summary.  We consider the problem of testing each of m null hypotheses with a sequential permutation procedure in which the number of draws from the permutation distribution of each test statistic is a random variable. Each sequential permutation p‐value has a null distribution that is ...

mehr

05.02.2013 | Susan Gruber, Mark J. van der Laan, Biometrics, 2013

Summary Safety analysis to estimate the effect of a treatment on an adverse event poses a challenging statistical problem even in randomized controlled trials because these events are typically rare, so studies originally powered for efficacy are underpowered for safety outcomes. A ...

mehr

05.02.2013 | Ian W. Renner, David I. Warton, Biometrics, 2013

Summary Modeling the spatial distribution of a species is a fundamental problem in ecology. A number of modeling methods have been developed, an extremely popular one being MAXENT, a maximum entropy modeling approach. In this article, we show that MAXENT is equivalent to a Poisson ...

mehr

04.02.2013 | Kari Auranen, Hanna Rinta‐Kokko, M. Elizabeth Halloran, Biometrics, 2013

Summary Evaluating vaccine efficacy for protection against colonization with bacterial pathogens is an area of growing interest. Colonization of the nasopharynx is an asymptomatic carrier state responsible for person‐to‐person transmission. It differs from most clinical outcomes in that it ...

mehr

04.02.2013 | Corwin M. Zigler, Krista Watts, Robert W. Yeh, Yun Wang, Brent A. Coull, Francesca Dominici, Biometrics, 2013

Summary Methods based on the propensity score comprise one set of valuable tools for comparative effectiveness research and for estimating causal effects more generally. These methods typically consist of two distinct stages: (1) a propensity score stage where a model is fit to predict the ...

mehr