A metastasis or a second independent cancer? Evaluating the clonal origin of tumors using array copy number data.

abstract：:Multilevel and longitudinal studies are frequently subject to missing data. For example, biomarker studies for oral cancer may involve multiple assays for each participant. Assays may fail, resulting in missing data values that can be assumed to be missing completely at random. Catellier and Muller proposed a data ana...

journal_title：Statistics in medicine

authors： Ringham BM,Kreidler SM,Muller KE,Glueck DH

更新日期：2016-07-30 00:00:00

abstract：:It is unclear to what extent the incremental predictive performance of a novel biomarker is impacted by the method used to control for standard predictors. We investigated whether adding a biomarker to a model with a published risk score overestimates its incremental performance as compared to adding it to a multivari...

journal_title：Statistics in medicine

authors： Xanthakis V,Sullivan LM,Vasan RS,Benjamin EJ,Massaro JM,D'Agostino RB Sr,Pencina MJ

更新日期：2014-07-10 00:00:00

abstract：:In this paper, we discuss statistical inference for a 2 × 2 table under inverse sampling, where the total number of cases is fixed by design. We demonstrate that the exact unconditional distributions of some relevant statistics differ from the distributions under conventional sampling, where the sample size is fixed b...

journal_title：Statistics in medicine

authors： Heimann G,Von Tress M,Gasparini M

更新日期：2015-08-30 00:00:00

abstract：:In this paper statistical methods are proposed to estimate the distribution of a CD4 T-cell number at the time of a clinical AIDS endpoint from serial measurements of CD4 T-cell values in a cohort study. The statistical formulation of the problem is that of survival analysis with interval censored data, but in which t...

journal_title：Statistics in medicine

authors： Taylor JM,Kim DK

更新日期：1994-10-15 00:00:00

abstract：:A method for detecting deviations from the Loewe additive drug combination reference model for in vitro drug combination experimentation is described. It is often difficult to fit a response surface model to drug combination data, especially in situations where the experimental design contains a sparse set of combinat...

journal_title：Statistics in medicine

authors： Novick SJ

更新日期：2013-12-20 00:00:00

abstract：:Several relative risk models for survival time data in drug combination therapy are derived and their properties are discussed. The main intention of this paper is to clarify the differences among the models in order to help to choose the appropriate one in a given situation. The models are motivated by discussing the...

journal_title：Statistics in medicine

authors： Kübler J,Schumacher M

更新日期：1990-12-01 00:00:00

abstract：:Joint models initially dedicated to a single longitudinal marker and a single time-to-event need to be extended to account for the rich longitudinal data of cohort studies. Multiple causes of clinical progression are indeed usually observed, and multiple longitudinal markers are collected when the true latent trait of...

journal_title：Statistics in medicine

authors： Proust-Lima C,Dartigues JF,Jacqmin-Gadda H

更新日期：2016-02-10 00:00:00

abstract：:With increasingly abundant spatial data in the form of case counts or rates combined over areal regions (eg, ZIP codes, census tracts, or counties), interest turns to formal identification of difference "boundaries," or barriers on the map, in addition to the estimated statistical map itself. "Boundary" refers to a bo...

journal_title：Statistics in medicine

authors： Guhaniyogi R

更新日期：2017-11-10 00:00:00

abstract：:In this paper, we define a modified version τ(b) of Kendall's tau to measure the association in a pair (X,Y) of random variables subject to fixed left censoring due to known lower detection limits. We provide a nonparametric estimator of τ(b) and investigate its asymptotic properties. We then assume an Archimedean cop...

journal_title：Statistics in medicine

authors： Romdhani H,Lakhal-Chaieb L

更新日期：2011-11-20 00:00:00

abstract：:In biomedical literature, numerous prediction models for clinical outcomes have been developed based either on clinical data or, more recently, on high-throughput molecular data (omics data). Prediction models based on both types of data, however, are less common, although some recent studies suggest that a suitable c...

journal_title：Statistics in medicine

authors： De Bin R,Sauerbrei W,Boulesteix AL

更新日期：2014-12-30 00:00:00

abstract：:We suggest measures to quantify the degrees of necessity and of sufficiency of prognostic factors for dichotomous and for survival outcomes. A cause, represented by certain values of prognostic factors, is considered necessary for an event if, without the cause, the event cannot develop. It is considered sufficient fo...

journal_title：Statistics in medicine

authors： Gleiss A,Schemper M

更新日期：2019-10-15 00:00:00

abstract：:We consider the analysis of serial biomarkers to screen and monitor individuals in a given population for onset of a specific disease of interest. The biomarker readings are subject to error. We survey some of the existing literature and concentrate on two recently proposed models. The first is a fully Bayesian hierar...

journal_title：Statistics in medicine

authors： Slate EH,Turnbull BW

更新日期：2000-02-29 00:00:00

abstract：:The effective dose (ED) is the pharmaceutical dosage required to produce a therapeutic response in a fixed proportion of the patients. When only one drug is considered, the problem is a univariate one and has been well-studied. However, in the multidimensional setting, that is, in the presence of combinations of agent...

journal_title：Statistics in medicine

authors： Jankowski H,Ji X,Stanberry L

更新日期：2014-10-30 00:00:00

abstract：:Juvenile dermatomyositis (JDM) is a rare autoimmune disease that may lead to serious complications, even to death. We develop a 2-state Markov regression model in a Bayesian framework to characterise disease progression in JDM over time and gain a better understanding of the factors influencing disease risk. The trans...

journal_title：Statistics in medicine

authors： De Iorio M,Gallot N,Valcarcel B,Wedderburn L

更新日期：2018-05-10 00:00:00

abstract：:Multi-state models are useful for modelling disease progression where the state space of the process is used to represent the discrete disease status of subjects. Often, the disease process is only observed at clinical visits, and the schedule of these visits can depend on the disease status of patients. In such situa...

journal_title：Statistics in medicine

authors： Lesperance ML,Sabelnykova V,Nathoo FS,Lau F,Downing MG

更新日期：2015-12-20 00:00:00

abstract：:The receiver operating characteristic (ROC) curve is a popular technique with applications, for example, investigating an accuracy of a biomarker to delineate between disease and non-disease groups. A common measure of accuracy of a given diagnostic marker is the area under the ROC curve (AUC). In contrast with the AU...

journal_title：Statistics in medicine

authors： Yu J,Yang L,Vexler A,Hutson AD

更新日期：2016-06-15 00:00:00

abstract：:Predicting an individual's risk of experiencing a future clinical outcome is a statistical task with important consequences for both practicing clinicians and public health experts. Modern observational databases such as electronic health records provide an alternative to the longitudinal cohort studies traditionally ...

journal_title：Statistics in medicine

authors： Wolfson J,Bandyopadhyay S,Elidrisi M,Vazquez-Benitez G,Vock DM,Musgrove D,Adomavicius G,Johnson PE,O'Connor PJ

更新日期：2015-09-20 00:00:00

abstract：:We present a new approach to training back-propagation artificial neural nets (BP-ANN) based on regularization and cross-validation and on initialization by a logistic regression (LR) model. The new approach is expected to produce a BP-ANN predictor at least as good as the LR-based one. We have applied the approach to...

journal_title：Statistics in medicine

authors： Ciampi A,Zhang F

更新日期：2002-05-15 00:00:00

abstract：:This paper considers the problem of selecting a set of regressors when the response variable is distributed according to a specified parametric model and observations are censored. Under a Bayesian perspective, the most widely used tools are Bayes factors (BFs), which are undefined when improper priors are used. In or...

journal_title：Statistics in medicine

authors： Cabras S,Castellanos ME,Perra S

更新日期：2014-11-20 00:00:00

abstract：:Slow recruitment in clinical trials leads to increased costs and resource utilization, which includes both the clinic staff and patient volunteers. Careful planning and monitoring of the accrual process can prevent the unnecessary loss of these resources. We propose two hierarchical extensions to the existing Bayesian...

journal_title：Statistics in medicine

authors： Jiang Y,Simon S,Mayo MS,Gajewski BJ

更新日期：2015-02-20 00:00:00

abstract：:We consider the use of the assurance method in clinical trial planning. In the assurance method, which is an alternative to a power calculation, we calculate the probability of a clinical trial resulting in a successful outcome, via eliciting a prior probability distribution about the relevant treatment effect. This i...

journal_title：Statistics in medicine

authors： Ren S,Oakley JE

更新日期：2014-01-15 00:00:00

abstract：:In a longitudinal study of workers in seven Norwegian aluminium plants, the time to development of asthmatic symptoms could only be determined to lie in the interval between two consecutive health examinations. In a previous paper we analysed the data by survival techniques for interval censored data. In the present p...

journal_title：Statistics in medicine

authors： Samuelsen SO,Kongerud J

更新日期：1994-09-15 00:00:00

abstract：:Cross-sectional designs are often used to monitor the proportion of infections and other post-surgical complications acquired in hospitals. However, conventional methods for estimating incidence proportions when applied to cross-sectional data may provide estimators that are highly biased, as cross-sectional designs t...

journal_title：Statistics in medicine

authors： Fluss R,Mandel M,Freedman LS,Weiss IS,Zohar AE,Haklai Z,Gordon ES,Simchen E

更新日期：2013-06-30 00:00:00

abstract：:In clinical research, investigators are interested in inferring the average causal effect of a treatment. However, the causal parameter that can be used to derive the average causal effect is not well defined for ordinal outcomes. Although some definitions have been proposed, they are limited in that they are not iden...

journal_title：Statistics in medicine

authors： Chiba Y

更新日期：2017-11-10 00:00:00

abstract：:We discuss a sample size calculation for a pair-matched case-control study to test for interaction between a specific exposure and a second risk factor. The second risk factor could be either binary or continuous. An algorithm for the calculation of sample size is suggested which is based on a logistic regression mode...

journal_title：Statistics in medicine

authors： Qiu P,Moeschberger ML,Cooke GE,Goldschmidt-Clermont PJ

更新日期：2000-04-15 00:00:00

abstract：:R2 has been criticized as a measure of model performance when predicting a dichotomous outcome, both because its value is often low and because it is sensitive to the prevalence of the event of interest. The C statistic is more widely used to measure model performance in a 0/1 setting. We use a simple parametric famil...

journal_title：Statistics in medicine

authors： Ash A,Shwartz M

更新日期：1999-02-28 00:00:00

abstract：:The serial dilution assay (for example, an in vitro antimicrobic susceptibility test or a serum antibody titer assay) is an important technique in biomedical research. The structure of the experiment forces grouping of the threshold concentrations into intervals. Statistical methods to analyse threshold concentrations...

journal_title：Statistics in medicine

authors： Hamilton MA,Rinaldi MG

更新日期：1988-04-01 00:00:00

abstract：:Generalized linear models are often assumed to fit propensity scores, which are used to compute inverse probability weighted (IPW) estimators. To derive the asymptotic properties of IPW estimators, the propensity score is supposed to be bounded away from zero. This condition is known in the literature as strict positi...

journal_title：Statistics in medicine

authors： Molina J,Sued M,Valdora M

更新日期：2018-10-30 00:00:00

abstract：:For the meta-analysis of controlled clinical trials or epidemiological studies, in which the responses are at least approximately normally distributed, a refined test for the hypothesis of no overall treatment effect is proposed. The test statistic is based on a direct estimation function for the variance of the overa...

journal_title：Statistics in medicine

authors： Hartung J,Knapp G

更新日期：2001-06-30 00:00:00

abstract：:The two-period cross-over design with two sequences of drug administration is a standard experimental design when bioequivalence of one test formulation is to be assessed in comparison with a reference formulation. Previously, an approach based on Fieller's confidence interval has been presented for the assessment of ...

journal_title：Statistics in medicine

authors： Vuorinen J

更新日期：1997-10-15 00:00:00