Randomization tests for multiarmed randomized clinical trials.

abstract：:In this paper we study the problem of variable selection for the proportional odds model, which is a useful alternative to the proportional hazards model and might be appropriate when the proportional hazards assumption is not satisfied. We propose to fit the proportional odds model by maximizing the marginal likeliho...

journal_title：Statistics in medicine

authors： Lu W,Zhang HH

更新日期：2007-09-10 00:00:00

abstract：:Although radical changes in drug regulation are rare (e.g., the Federal Food, Drug and Cosmetic Act of 1938 and the 1962 amendment to the Act creating an effectiveness requirement), regulations and guidance do evolve significantly in the face of new problems and accumulating experience. Recent changes have been driven...

journal_title：Statistics in medicine

authors： Temple R

更新日期：2002-10-15 00:00:00

abstract：:Conditional power (CP) is the probability that the final study result will be statistically significant, given the data observed thus far and a specific assumption about the pattern of the data to be observed in the remainder of the study, such as assuming the original design effect, or the effect estimated from the c...

journal_title：Statistics in medicine

authors： Lachin JM

更新日期：2005-09-30 00:00:00

abstract：:Meta-analyses pooling continuous outcomes can use mean differences (MD), standardized MD (MD in pooled standard deviation units, SMD), or ratio of arithmetic means (RoM). Recently, ratio of geometric means using ad hoc (RoGM (ad hoc) ) or Taylor series (RoGM (Taylor) ) methods for estimating variances have been propos...

journal_title：Statistics in medicine

authors： Friedrich JO,Adhikari NK,Beyene J

更新日期：2012-07-30 00:00:00

abstract：:The Spearman (rho(s)) and Kendall (tau) rank correlation coefficient are routinely used as measures of association between non-normally distributed random variables. However, confidence limits for rho(s) are only available under the assumption of bivariate normality and for tau under the assumption of asymptotic norma...

journal_title：Statistics in medicine

authors： Rosner B,Glynn RJ

更新日期：2007-02-10 00:00:00

abstract：:In the study of multiple failure times for the same subjects, for example, recurrent infections for patients with a given disease, there are often subject effects, that is, subjects have different risks that cannot be explained by known covariates. Standard methods, which ignore subject effects, lead to overestimation...

journal_title：Statistics in medicine

authors： Yau KK,McGilchrist CA

更新日期：1998-06-15 00:00:00

abstract：:Funnel plots are widely used to visualize grouped data, for example, in institutional comparison. This paper extends the concept to a multi-level setting, displaying one level at a time, adjusted for the other levels, as well as for covariates at all levels. These level-adjusted funnel plots are based on a Markov chai...

journal_title：Statistics in medicine

authors： Lindhagen L,Darkahi B,Sandblom G,Berglund L

更新日期：2014-09-20 00:00:00

abstract：:Prevalence data provided by cancer registries are generally biased, since the patients that were diagnosed before the starting of the registry's activity cannot be included in the statistics. The relevance of this incompleteness bias is estimated in this paper. Incidence and relative survival are modelled as parametri...

journal_title：Statistics in medicine

authors： Capocaccia R,De Angelis R

更新日期：1997-02-28 00:00:00

abstract：:Instrumental variable estimates of causal effects can be biased when using many instruments that are only weakly associated with the exposure. We describe several techniques to reduce this bias and estimate corrected standard errors. We present our findings using a simulation study and an empirical application. For th...

journal_title：Statistics in medicine

authors： Davies NM,von Hinke Kessler Scholder S,Farbmacher H,Burgess S,Windmeijer F,Smith GD

更新日期：2015-02-10 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：:Conditional power and predictive power provide estimates of the probability of success at the end of the trial based on the information from the interim analysis. The observed value of the time to event endpoint at the interim analysis could be biased for the true treatment effect due to early censoring, leading to a ...

journal_title：Statistics in medicine

authors： Sun L,Wan Y

更新日期：2018-08-15 00:00:00

abstract：:Bayesian methods are proposed for analysing matched case-control studies in which a binary exposure variable is sometimes measured with error, but whose correct values have been validated for a random sample of the matched case-control sets. Three models are considered. Model 1 makes few assumptions other than randomn...

journal_title：Statistics in medicine

authors： Prescott GJ,Garthwaite PH

更新日期：2005-02-15 00:00:00

abstract：:Although population-based molecular association studies are becoming increasingly popular, methodology for the meta-analysis of these studies has been neglected, particularly with regard to two issues: testing Hardy-Weinberg equilibrium (HWE), and pooling results in a manner that reflects a biological model of gene ef...

journal_title：Statistics in medicine

authors： Thakkinstian A,McElduff P,D'Este C,Duffy D,Attia J

更新日期：2005-05-15 00:00:00

abstract：:In comparing two treatments under a typical sequential clinical trial setting, a 50-50 randomization design generates reliable data for making efficient inferences about the treatment difference for the benefit of patients in the general population. However, if the treatment difference is large and the endpoint of the...

journal_title：Statistics in medicine

authors： Yao Q,Wei LJ

更新日期：1996-11-15 00:00:00

abstract：:Recurrent event data occur in many clinical and observational studies, and in these situations, there may exist a terminal event such as death that is related to the recurrent event of interest. In addition, sometimes more than one type of recurrent events may occur, that is, one may encounter multivariate recurrent e...

journal_title：Statistics in medicine

authors： Zhu L,Sun J,Srivastava DK,Tong X,Leisenring W,Zhang H,Robison LL

更新日期：2011-11-10 00:00:00

abstract：:We construct nonparametric regression estimators of a number of temporal functions in a multistate system based on a continuous univariate baseline covariate. These estimators include state occupation probabilities, state entry, exit, and waiting (sojourn) time distribution functions of a general progressive (e.g., ac...

journal_title：Statistics in medicine

authors： Mostajabi F,Datta S

更新日期：2013-07-30 00:00:00

abstract：:This paper examines several methods for deriving standardized morbidity ratios (SMR) and attributable fraction (attributable risk percentage) estimates. We show that some of the proposed methods will, in general, produce biased estimators, although the low variance of certain estimators sometimes compensates for their...

journal_title：Statistics in medicine

authors： Greenland S

更新日期：1984-04-01 00:00:00

abstract：:Girardeau, Ravaud and Donner in 2008 presented a formula for sample size calculations for cluster randomised crossover trials, when the intracluster correlation coefficient, interperiod correlation coefficient and mean cluster size are specified in advance. However, in many randomised trials, the number of clusters is...

journal_title：Statistics in medicine

authors： Kelly TL,Pratt N

更新日期：2019-08-15 00:00:00

abstract：:This paper presents combinatorial (exact) methods that are useful in the analysis of disease cluster data obtained from small environments, such as buildings and neighbourhoods. Maxwell-Boltzmann and Fermi-Dirac occupancy models are compared in terms of appropriateness of representation of disease incidence patterns (...

journal_title：Statistics in medicine

authors： Grimson RC

更新日期：1993-10-01 00:00:00

abstract：:Subjective judgements of complex variables are commonly recorded as ordered categorical data. The rank-invariant properties of such data are well known, and there are various statistical approaches to the analysis and modelling of ordinal data. This paper focuses on the non-additive property of ordered categorical dat...

journal_title：Statistics in medicine

authors： Svensson E

更新日期：1998-12-30 00:00:00

abstract：:In this paper we examine the efficiency of a generalization of the traditional normal linear (LDA) or quadratic (QDA) discriminant analysis. This procedure (the generalized discriminant analysis, GDA) replaces each normal density used in the traditional classification rule by a Fourier series density estimator which '...

journal_title：Statistics in medicine

authors： Odom-Maryon T,Langholz B,Niland J,Azen S

更新日期：1991-03-01 00:00:00

abstract：:The percentile-finding experimental design known variously as 'forced-choice fixed-staircase', 'geometric up-and-down' or 'k-in-a-row' (KR) was introduced by Wetherill four decades ago. To date, KR has been by far the most widely used up-and-down (U&D) design for estimating non-median percentiles; it is implemented mo...

journal_title：Statistics in medicine

authors： Oron AP,Hoff PD

更新日期：2009-06-15 00:00:00

abstract：:In observational studies with censored data, exposure-outcome associations are commonly measured with adjusted hazard ratios from multivariable Cox proportional hazards models. The difference in restricted mean survival times (RMSTs) up to a pre-specified time point is an alternative measure that offers a clinically m...

journal_title：Statistics in medicine

authors： Conner SC,Sullivan LM,Benjamin EJ,LaValley MP,Galea S,Trinquart L

更新日期：2019-09-10 00:00:00

abstract：:We propose a semiparametric method for estimating ROC surfaces for continuous diagnostic tests based on two test measurements. Such a three-class diagnostic problem based on two test measurements arises naturally from some DNA amplification-related diagnostic scenarios. Simulation results show that our proposed semipa...

journal_title：Statistics in medicine

authors： Wan S,Zhang B

更新日期：2009-08-15 00:00:00

abstract：:We applied a computationally practical form of probit analysis for multiple response variables to data on early childhood development of four psychiatric disorders: disruptive disorders (DD-attention deficit disorders, oppositional defiant disorder, conduct disorder); adjustment disorders (ADJ); emotional disorders (E...

journal_title：Statistics in medicine

authors： Gibbons RD,Lavigne JV

更新日期：1998-11-15 00:00:00

abstract：:It has been increasingly common to analyze simultaneously repeated measures and time to failure data. In this paper we propose a joint model when the repeated measures are semi-continuous, characterized by the presence of a large portion of zero values, as well as right skewness of non zero (positive) values. Examples...

journal_title：Statistics in medicine

authors： Liu L

更新日期：2009-03-15 00:00:00

abstract：:A survey is conducted at w of K selection units or lists, e.g. health care institutions or weeks in a year, to estimate N, the total number of individuals with particular characteristics. Our estimator utilizes two items determined for each survey participant: the number, u, among the w lists in S and the number, j, a...

journal_title：Statistics in medicine

authors： Laska EM,Meisner M,Wanderling J

更新日期：2009-07-30 00:00:00

abstract：:This paper reviews methods for mapping geographical variation in disease incidence and mortality. Recent results in Bayesian hierarchical modelling of relative risk are discussed. Two approaches to relative risk estimation, along with the related computational procedures, are described and compared. The first is an em...

journal_title：Statistics in medicine

authors： Bernardinelli L,Montomoli C

更新日期：1992-06-15 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：:We consider the estimation of parameters in a particular segmented generalized linear model with additive measurement error in predictors, with a focus on linear and logistic regression. In epidemiologic studies segmented regression models often occur as threshold models, where it is assumed that the exposure has no i...

journal_title：Statistics in medicine

authors： Küchenhoff H,Carroll RJ

更新日期：1997-01-15 00:00:00