The analysis of continuous outcomes in multi-centre trials with small centre sizes.

abstract：:Identification of the latency period for the effect of a time-varying exposure is key when assessing many environmental, nutritional, and behavioral risk factors. A pre-specified exposure metric involving an unknown latency parameter is often used in the statistical model for the exposure-disease relationship. Likelih...

journal_title：Statistics in medicine

authors： Peskoe SB,Spiegelman D,Wang M

更新日期：2019-03-30 00:00:00

abstract：:Propensity score analysis is widely used in observational studies to adjust for confounding and estimate the causal effect of a treatment on the outcome. When the outcome is survival time, there are special considerations on the definition of the causal estimand, point, and variance estimation that have not been thoro...

journal_title：Statistics in medicine

authors： Mao H,Li L,Yang W,Shen Y

更新日期：2018-11-20 00:00:00

abstract：:We propose the use of Gaussian mixed models to analyse statistically 24 hour ambulatory blood pressure data from clinical trials. We develop specific models and apply them to data from a clinical study that compares two angiotensin-converting enzyme inhibitors. We investigate and discuss computing issues related to th...

journal_title：Statistics in medicine

authors： Selwyn MR,Difranco DM

更新日期：1993-09-30 00:00:00

abstract：:When investigating health disparities, it can be of interest to explore whether adjustment for socioeconomic factors at the neighborhood level can account for, or even reverse, an unadjusted difference. Recently, we proposed new methods to adjust the effect of an individual-level covariate for confounding by unmeasure...

journal_title：Statistics in medicine

authors： Brumback BA,Zheng HW,Dailey AB

更新日期：2013-04-15 00:00:00

abstract：:Mediation analyses can help us to understand the biological mechanism in which an exposure or treatment affects an outcome. Single mediator analyses have been used in various applications, but may not be appropriate for analyzing intricate mechanisms involving multiple mediators that affect each other. Thus, in this a...

journal_title：Statistics in medicine

authors： Lai EY,Shih S,Huang YT,Wang S

更新日期：2020-05-15 00:00:00

abstract：:A general method is presented that allows the researcher to change statistical design elements such as the residual sample size during the course of an experiment, to include an interim analysis for early stopping when no formal rule for early stopping was foreseen, to increase or reduce the number of planned interim ...

journal_title：Statistics in medicine

authors： Müller HH,Schäfer H

更新日期：2004-08-30 00:00:00

abstract：:Geocoding a study population as completely as possible is an important data assimilation component of many spatial epidemiologic studies. Unfortunately, complete geocoding is rare in practice. The failure of a substantial proportion of study subjects' addresses to geocode has consequences for spatial analyses, some of...

journal_title：Statistics in medicine

authors： Zimmerman DL,Fang X,Mazumdar S

更新日期：2008-09-20 00:00:00

abstract：:We consider Cox proportional hazards regression when the covariate vector includes error-prone discrete covariates along with error-free covariates, which may be discrete or continuous. The misclassification in the discrete error-prone covariates is allowed to be of any specified form. Building on the work of Nakamura...

journal_title：Statistics in medicine

authors： Zucker DM,Spiegelman D

更新日期：2008-05-20 00:00:00

abstract：:Adaptive designs or flexible designs in a broader sense have increasingly been considered in planning pivotal registration clinical trials. Sample size reassessment design and adaptive selection design are two of such designs that appear in regulatory applications. At the design stage, consideration of sample size rea...

journal_title：Statistics in medicine

authors： Hung HM,Wang SJ,O'Neill R

更新日期：2011-06-15 00:00:00

abstract：:In this work, we describe a two-stage sampling design to estimate the infection prevalence in a population. In the first stage, an imperfect diagnostic test was performed on a random sample of the population. In the second stage, a different imperfect test was performed in a stratified random sample of the first sampl...

journal_title：Statistics in medicine

authors： Miller E,Huppert A,Novikov I,Warburg A,Hailu A,Abbasi I,Freedman LS

更新日期：2015-11-10 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：:Many extensions of survival models based on the Cox proportional hazards approach have been proposed to handle clustered or multiple event data. Of particular note are five Cox-based models for recurrent event data: Andersen and Gill (AG); Wei, Lin and Weissfeld (WLW); Prentice, Williams and Peterson, total time (PWP-...

journal_title：Statistics in medicine

authors： Kelly PJ,Lim LL

更新日期：2000-01-15 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：:Comparison of two hazard rate functions is important for evaluating treatment effect in studies concerning times to some important events. In practice, it may happen that the two hazard rate functions cross each other at one or more unknown time points, representing temporal changes of the treatment effect. Also, besi...

journal_title：Statistics in medicine

authors： Park KY,Qiu P

更新日期：2014-11-20 00:00:00

abstract：:For each of 211 arteriosclerosis obliterans patients, the degree of stenosis of arteries at four sites were examined at Hiroshima University Hospital to analyse the relationship between the degree of stenosis and age, sex and site. The generalized estimating equations using a proportional odds model for the stenosis p...

journal_title：Statistics in medicine

authors： Nakashima E,Tsuji S,Fukuoka H,Ohtaki M,Ito K

更新日期：2003-07-15 00:00:00

abstract：:Clinical trials, especially the randomized clinical trial, have been and will remain the gold standard for the evaluation of new interventions, including pharmaceuticals, biologics, medical devices, procedures, or behavioral modifications. Despite more than five decades of experience, there are still challenges in the...

journal_title：Statistics in medicine

authors： DeMets DL

更新日期：2012-11-10 00:00:00

abstract：:The two tailed Fisher's exact P value is extremely sensitive to small perturbations in 2 x 2 contingency tables. An example indicates that a 1 per cent increase in the denominator of one treatment group results in a 32 per cent drop in the exact P value, but a mere 0.1 per cent decrease in the treatment success rate. ...

journal_title：Statistics in medicine

authors： Dupont WD

更新日期：1986-11-01 00:00:00

abstract：:This paper considers the analysis of longitudinal data complicated by the fact that during follow-up patients can be in different disease states, such as remission, relapse or death. If both the response of interest (for example, quality of life (QOL)) and the amount of missing data depend on this disease state, ignor...

journal_title：Statistics in medicine

authors： le Cessie S,de Vries EG,Buijs C,Post WJ

更新日期：2009-12-30 00:00:00

abstract：:We study the group bridge and the adaptive group bridge penalties for competing risks quantile regression with group variables. While the group bridge consistently identifies nonzero group variables, the adaptive group bridge consistently selects variables not only at group level but also at within-group level. We all...

journal_title：Statistics in medicine

authors： Ahn KW,Kim S

更新日期：2018-04-30 00:00:00

abstract：:Testing involving the intra-class kappa coefficient is commonly performed in order to assess agreement involving categorical ratings. A number of procedures have been proposed, which make use of the limiting null distribution as the sample size goes to infinity in order to compute the observed significance. As with ma...

journal_title：Statistics in medicine

authors： Wilding GE,Consiglio JD,Shan G

更新日期：2014-07-30 00:00:00

abstract：:The National Children's Study is a national household probability sample designed to identify 100,000 children at birth and follow the sampled children for 21 years. Data from the study will support examining numerous hypotheses concerning genetic and environmental effects on the health and development of children. Th...

journal_title：Statistics in medicine

authors： Montaquila JM,Brick JM,Curtin LR

更新日期：2010-06-15 00:00:00

abstract：:Pearson's chi-squared, the likelihood-ratio, and Fisher-Freeman-Halton's test statistics are often used to test the association of unordered r x c tables. Asymptotical, exact conditional, or exact conditional with mid-p adjustment methods are commonly used to compute the p-value. We have compared test power and signif...

journal_title：Statistics in medicine

authors： Lydersen S,Pradhan V,Senchaudhuri P,Laake P

更新日期：2007-10-15 00:00:00

abstract：:The purpose of this paper is to show that the sensitivity and specificity estimates obtained by 'discrepant analysis' are biased. Discrepant analysis is a widely used technique that attempts to provide estimates of sensitivity and specificity in the presence of an imperfect gold standard. Many researchers have applied...

journal_title：Statistics in medicine

authors： Hadgu A

更新日期：1997-06-30 00:00:00

abstract：:Motivated by a study about prompt coronary angiography in myocardial infarction, we propose a method to estimate the causal effect of a treatment in two-arm experimental studies with possible noncompliance in both treatment and control arms. We base the method on a causal model for repeated binary outcomes (before and...

journal_title：Statistics in medicine

authors： Bartolucci F,Farcomeni A

更新日期：2013-11-10 00:00:00

abstract：:The "some invalid, some valid instrumental variable estimator" (sisVIVE) is a lasso-based method for instrumental variables (IVs) regression of outcome on an exposure. In principle, sisVIVE is robust to some of the IVs in the analysis being invalid, in the sense of being related to the outcome variable through pathway...

journal_title：Statistics in medicine

authors： Bao Y,Clarke PS,Smart M,Kumari M

更新日期：2019-04-30 00:00:00

abstract：:We discuss some of the statistical approaches to the design and analysis of phase I clinical trials in cancer. An attempt is made to identify the issues, particular to this type of trial, that should be addressed by an appropriate methodology. A brief review of schemes currently in use is provided together with our vi...

journal_title：Statistics in medicine

authors： O'Quigley J,Chevret S

更新日期：1991-11-01 00:00:00

abstract：:In a long-running longitudinal study using complex machinery to obtain measurements, it is sometimes necessary to replace the machine. This can result in lack of continuity in the measurements that can overwhelm any treatment effect or time trend. We propose a Bayesian procedure implemented using Markov chain Monte Ca...

journal_title：Statistics in medicine

authors： Ambrosius WT,Hui SL

更新日期：2004-09-30 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：: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：:Between-community variance or community-by-time variance is one of the key factors driving the cost of conducting group randomized trials, which are often very expensive. We investigated empirically whether between-community variance could be reduced by controlling individual- and/or community-level covariates and ide...

journal_title：Statistics in medicine

authors： Feng Z,Diehr P,Yasui Y,Evans B,Beresford S,Koepsell TD

更新日期：1999-03-15 00:00:00