Exploring the benefits of adaptive sequential designs in time-to-event endpoint settings.

abstract：:Multiple imputation by chained equations is a flexible and practical approach to handling missing data. We describe the principles of the method and show how to impute categorical and quantitative variables, including skewed variables. We give guidance on how to specify the imputation model and how many imputations ar...

journal_title：Statistics in medicine

authors： White IR,Royston P,Wood AM

更新日期：2011-02-20 00:00:00

abstract：:Modelling disease clustering over space and time can be helpful in providing indications of possible exposures and planning corresponding public health practices. Though a considerable number of studies focus on modelling spatio-temporal patterns of disease, most of them do not directly model a spatio-temporal cluster...

journal_title：Statistics in medicine

authors： Yan P,Clayton MK

更新日期：2006-03-15 00:00:00

abstract：:In an individually matched case-control study, effects of potential risk factors are ascertained through conditional logistic regression (CLR). Extension of CLR to situations with multiple disease or reference categories has been made through polychotomous CLR and is shown to be more efficient than carrying out separa...

journal_title：Statistics in medicine

authors： Mukherjee B,Liu I,Sinha S

更新日期：2007-07-30 00:00:00

abstract：:The World Health Organization and collaborating institutions in four developing countries have conducted a multi-centre randomized controlled trial, in which clinics were allocated at random to two antenatal care (ANC) models. These were the standard 'Western' ANC model and a 'new' ANC model consisting of tests, clini...

journal_title：Statistics in medicine

authors： Piaggio G,Carroli G,Villar J,Pinol A,Bakketeig L,Lumbiganon P,Bergsjø P,Al-Mazrou Y,Ba'aqeel H,Belizán JM,Farnot U,Berendes H,WHO Antenatal Care Trial Research Group.

更新日期：2001-02-15 00:00:00

abstract：:We consider evaluation and comparison of the diagnostic accuracy of biomarkers with continuous test outcomes, possibly correlated due to repeated measurements. We develop nonparametric group sequential testing procedures to evaluate and compare the area of biomarkers under their receiver operating characteristic curve...

journal_title：Statistics in medicine

authors： Liu A,Wu C,Schisterman EF

更新日期：2008-05-10 00:00:00

abstract：:We obtained maximum likelihood estimates (MLEs) of the proportion cured pi c and mean log survival time mu t for a sample of 4355 patients with intraocular melanoma whose survival times subsequent to treatment were assumed to follow a log-normal distribution. Following stratification by tumour size, MLEs of pi c and m...

journal_title：Statistics in medicine

authors： Gamel JW,McLean IW,Rosenberg SH

更新日期：1990-08-01 00:00:00

abstract：:A mixture model incorporating long-term survivors has been adopted in the field of biostatistics where some individuals may never experience the failure event under study. The surviving fractions may be considered as cured. In most applications, the survival times are assumed to be independent. However, when the survi...

journal_title：Statistics in medicine

authors： Yau KK,Ng AS

更新日期：2001-06-15 00:00:00

abstract：:Longitudinal designs are important in medical research and in many other disciplines. Complete longitudinal studies, in which each subject is evaluated at each measurement occasion, are often very expensive and motivate a search for more efficient designs. Recently developed statistical methods foster the use of inten...

journal_title：Statistics in medicine

authors： Helms RW

更新日期：1992-10-01 00:00:00

abstract：:Omitted variable bias is discussed in the context of linear models. It is shown that the effect of omitted variables can be controlled in linear models for metric dependent variables by using data from follow-up studies. Two different models for analysing such data are proposed. In the first model the omitted variable...

journal_title：Statistics in medicine

authors： Rehm J,Arminger G,Kohlmeier L

更新日期：1992-06-30 00:00:00

abstract：:In observational cohort studies we may wish to examine the associations between fixed patient characteristics and the longitudinal changes from baseline in a repeated outcome measure. Many biological and other outcome measures are known to be subject to measurement error and biological variation. In an initial analysi...

journal_title：Statistics in medicine

authors： Harrison L,Dunn DT,Green H,Copas AJ

更新日期：2009-11-20 00:00:00

abstract：:Multivariate random length data occur when we observe multiple measurements of a quantitative variable and the variable number of these measurements is also an observed outcome for each experimental unit. For example, for a patient with coronary artery disease, we may observe a number of lesions in that patient's coro...

journal_title：Statistics in medicine

authors： Barnhart HX,Kosinski AS,Sampson AR

更新日期：1999-01-30 00:00:00

abstract：:Both traditional phase I designs and the increasingly popular continual reassessment method (CRM) designs select an estimate of maximum tolerable dose (MTD) from among a set of prespecified dose levels. Although CRM designs use an implied dose-response model to select the next dose level, in general it is neither assu...

journal_title：Statistics in medicine

authors： Storer BE

更新日期：2001-08-30 00:00:00

abstract：:Hospital length of stay (LOS) is an important measure of healthcare utilization and is generally positively skewed and heterogeneous. We fit a Coxian phase-type distribution to LOS and identify the hidden states of the underlying latent homogeneous Markov model. We demonstrate that selecting an appropriate number of p...

journal_title：Statistics in medicine

authors： Tang X,Luo Z,Gardiner JC

更新日期：2012-06-30 00:00:00

abstract：:The publication of Fisher's correspondence on statistics has shed new light on his views on randomization. Quotations from this correspondence and from other works of Fisher are used to illustrate the role of randomization in clinical trials. It is concluded that Fisher's views not only are coherent but, despite havin...

journal_title：Statistics in medicine

authors： Senn S

更新日期：1994-02-15 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 the analysis of survival data, there are often competing events that preclude an event of interest from occurring. Regression analysis with competing risks is typically undertaken using a cause-specific proportional hazards model. However, modern alternative methods exist for the analysis of the subdistribution haz...

journal_title：Statistics in medicine

authors： Lau B,Cole SR,Gange SJ

更新日期：2011-03-15 00:00:00

abstract：:Thomas et al. presented the application of empirical-Bayes methods to the problem of multiple inference in epidemiologic studies. One limitation of their approach, which they noted, was the need to assume exchangeable log relative-risk parameters, and independent relative-risk estimates. Numerical integration was also...

journal_title：Statistics in medicine

authors： Greenland S

更新日期：1992-01-30 00:00:00

abstract：:Blinded estimation of variance allows for changing the sample size without compromising the integrity of the trial. Some of the methods that estimate the variance in a blinded manner either make untenable assumptions or are only applicable to two-treatment trials. We propose a new method for continuous endpoints that ...

journal_title：Statistics in medicine

authors： Xing B,Ganju J

更新日期：2005-06-30 00:00:00

abstract：:A three-component, competing-risk mortality model, developed for animal survival data, fits human life table data for all ages over a range of mean life spans from 16 to 74 years. The competing risks are a novel exponentially-decreasing hazard, dominant during immaturity; a constant hazard, dominant during adulthood; ...

journal_title：Statistics in medicine

authors： Siler W

更新日期：1983-07-01 00:00:00

abstract：:We consider several sources of heterogeneity in a clinical trial with patients' survival time as the main response criterion: differences in prognosis which can be attributed to a latent or ignored prognostic factor; differences in treatment efficacy in subgroups of patients, and differences in treatment combinations ...

journal_title：Statistics in medicine

authors： Schumacher M,Olschewski M,Schmoor C

更新日期：1987-10-01 00:00:00

abstract：:In this paper, we argue that causal effect models for realistic individualized treatment rules represent an attractive tool for analyzing sequentially randomized trials. Unlike a number of methods proposed previously, this approach does not rely on the assumption that intermediate outcomes are discrete or that models ...

journal_title：Statistics in medicine

authors： Bembom O,van der Laan MJ

更新日期：2008-08-30 00:00:00

abstract：:We extend the method proposed in a recent work by the Authors for trial-level general surrogate evaluation to allow combinations of biomarkers and provide a procedure for finding the "best" combination of biomarkers based on the absolute prediction error summary of surrogate quality. We use a nonparametric Bayesian mo...

journal_title：Statistics in medicine

authors： Gabriel EE,Sachs MC,Daniels MJ,Halloran ME

更新日期：2019-03-30 00:00:00

abstract：:Selection of dose for cancer patients treated with radiation therapy (RT) must balance the increased efficacy with the increased toxicity associated with higher dose. Historically, a single dose has been selected for a population of patients (e.g., all stage III non-small cell lung cancer). However, the availability o...

journal_title：Statistics in medicine

authors： Schipper MJ,Taylor JM,TenHaken R,Matuzak MM,Kong FM,Lawrence TS

更新日期：2014-12-30 00:00:00

abstract：:A good measure of field vaccine efficacy should evaluate the direct protective effect of vaccination on the person who receives the vaccine. The conventional estimator for vaccine efficacy depends on population level factors that are either unrelated or indirectly related to the direct biological action of the vaccine...

journal_title：Statistics in medicine

authors： Longini IM Jr,Halloran ME,Haber M,Chen RT

更新日期：1993-02-01 00:00:00

abstract：:Elevated plasma levels of apolipoproteins A1 (apoA1) and B (apoB) are important protective factors and risk factors, respectively, for atherosclerosis and coronary heart disease. It is well known that both apoA1 and apoB reveal strong familial aggregation. Our goal was to investigate whether exogenous variables influe...

journal_title：Statistics in medicine

authors： Ziegler A,Kastner C,Brunner D,Blettner M

更新日期：2000-12-30 00:00:00

abstract：:Studies involving longitudinal binary responses are widely applied in the health and biomedical sciences research and frequently analyzed by generalized estimating equations (GEE) method. This article proposes an alternative goodness-of-fit test based on the nonparametric smoothing approach for assessing the adequacy ...

journal_title：Statistics in medicine

authors： Lin KC,Chen YJ,Shyr Y

更新日期：2008-09-30 00:00:00

abstract：:Standard randomization-based tests of sharp null hypotheses in randomized clinical trials, that is, intent-to-treat analyses, are valid without extraneous assumptions, but generally can be appropriately powerful only with alternative hypotheses that involve treatment assignment having an effect on outcome. In the cont...

journal_title：Statistics in medicine

authors： Rubin DB

更新日期：1998-02-15 00:00:00

abstract：:Orthogonal polynomial scores (OPS) is a simple, biologically meaningful approach to characterize longitudinal data in phase I and II clinical pharmacology trials. It describes average, linear, quadratic and higher order polynomial characteristics of each subject's response over time with use of composite scores comput...

journal_title：Statistics in medicine

authors： Bradstreet TE

更新日期：1993-04-15 00:00:00

abstract：:In this paper we give an informal introduction to a robust method for survival analysis which is based on a modification of the usual partial likelihood estimator (PLE). Large sample results lead us to expect reduced bias for this robust estimator compared with the PLE whenever there are even slight violations of the ...

journal_title：Statistics in medicine

authors： Minder CE,Bednarski T

更新日期：1996-05-30 00:00:00

abstract：:Nutritional exposures are often measured with considerable error in commonly used surrogate instruments such as the food frequency questionnaire (FFQ) (denoted by Q(i) for the ith subject). The error can be both systematic and random. The diet record (DR) denoted by R(i) for the ith subject is considered an alloyed go...

journal_title：Statistics in medicine

authors： Rosner B,Michels KB,Chen YH,Day NE

更新日期：2008-08-15 00:00:00