Last observation carry-forward and last observation analysis.

abstract：:This paper develops methods of analysis for active extension clinical trials. Under this design, patients are randomized to treatment or placebo for a period of time (period 1), and then all patients receive treatment for an additional period of time (period 2). We assume a continuous outcome is measured at baseline a...

journal_title：Statistics in medicine

authors： Hu Z,Follmann D

更新日期：2007-05-30 00:00:00

abstract：:Crossover studies have been successfully conducted in the case of continuous responses. Existing procedures of analysis for ordinal responses, on the other hand, are rarely satisfactory unless strict, usually unrealistic, assumptions are made. In this paper we investigate a random effects model and show that the model...

journal_title：Statistics in medicine

authors： Ezzet F,Whitehead J

更新日期：1991-06-01 00:00:00

abstract：:The introduction of potent antiretroviral therapies for treatment of HIV infection typically results in a dramatic reduction in plasma HIV RNA concentration, often to levels undetectable by current measurement practices. However, although a high proportion of patients achieve 'undetectability', many then experience a ...

journal_title：Statistics in medicine

authors： McKinnon EJ,James IR,John M,Mallal SA

更新日期：2003-02-15 00:00:00

abstract：:Longitudinal studies are commonly used to study processes of change. Because data are collected over time, missing data are pervasive in longitudinal studies, and complete ascertainment of all variables is rare. In this paper a new imputation strategy for completing longitudinal data sets is proposed. The proposed met...

journal_title：Statistics in medicine

authors： Landrum MB,Becker MP

更新日期：2001-09-15 00:00:00

abstract：:Phase II trials often test the null hypothesis H(0): p or=p(1), where p is the true unknown proportion responding to the new treatment, p(0) is the greatest response proportion which is deemed clinically ineffective, and p(1) is the smallest response proportion which is deemed clinically effe...

journal_title：Statistics in medicine

authors： Ayanlowo AO,Redden DT

更新日期：2007-03-30 00:00:00

abstract：:We propose an innovative and practically relevant clustering method to find common task-related brain regions among different subjects who respond to the same set of stimuli. Using functional magnetic resonance imaging (fMRI) time series data, we first cluster the voxels within each subject on a voxel by voxel basis. ...

journal_title：Statistics in medicine

authors： Ye J,Li Y,Lazar NA,Schaeffer DJ,McDowell JE

更新日期：2016-07-10 00:00:00

abstract：:A considerable number of the clinical reports which are presented to the Dutch Board for the Evaluation of Drugs, have deficiencies and/or shortcomings. A number of these, including loose description of the target population and sampling method, methodological flaws, incorrect treatment of withdrawals, confounding of ...

journal_title：Statistics in medicine

authors： De Jonge H

更新日期：1983-04-01 00:00:00

abstract：:Three-arm trials including the experimental treatment, an active reference treatment and a placebo are recommended in the guidelines of the ICH and EMEA/CPMP as a useful approach to the assessment of assay sensitivity. Generally, the acceptable non-inferiority margin Δ has been defined as the maximum clinically irrele...

journal_title：Statistics in medicine

authors： Hida E,Tango T

更新日期：2011-02-10 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：:Correlation analysis is widely used in biomedical and psychosocial research for assessing rater reliability, precision of diagnosis and accuracy of proxy outcomes. The popularity of longitudinal study designs has propelled the proliferation in recent years of new methods for longitudinal and other multi-level clustere...

journal_title：Statistics in medicine

authors： Tu XM,Feng C,Kowalski J,Tang W,Wang H,Wan C,Ma Y

更新日期：2007-09-30 00:00:00

abstract：:In standard time-to-event or survival analysis, occurrence times of the event of interest are observed exactly or are right-censored, meaning that it is only known that the event occurred after the last observation time. There are numerous methods available for estimating the survival curve and for testing and estimat...

journal_title：Statistics in medicine

authors： Lindsey JC,Ryan LM

更新日期：1998-01-30 00:00:00

abstract：:Although the frequentist paradigm has been the predominant approach to clinical trial design since the 1940s, it has several notable limitations. Advancements in computational algorithms and computer hardware have greatly enhanced the alternative Bayesian paradigm. Compared with its frequentist counterpart, the Bayesi...

journal_title：Statistics in medicine

authors： Lee JJ,Chu CT

更新日期：2012-11-10 00:00:00

abstract：:Performance of a diagnostic test is ideally evaluated by a comparison of the test results to a gold standard for all the patients in a study. In practice, however, it is common for a subset of study patients to have the gold standard not verified (missing) due to ethical or expense considerations. Sensitivity and spec...

journal_title：Statistics in medicine

authors： Kosinski AS,Chen Y,Lyles RH

更新日期：2010-07-10 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：:In longitudinal studies, missing observations occur commonly. It has been well known that biased results could be produced if missingness is not properly handled in the analysis. Authors have developed many methods with the focus on either incomplete response or missing covariate observations, but rarely on both. The ...

journal_title：Statistics in medicine

authors： Li H,Yi GY

更新日期：2013-02-28 00:00:00

abstract：:It is not uncommon for a continuous outcome variable Y to be dichotomized and analysed using logistic regression. Moser and Coombs (Statist. Med. 2004; 23:1843-1860) provide a method for converting the output from a standard linear regression analysis using the original continuous outcome Y to give much more efficient...

journal_title：Statistics in medicine

authors： Jiang Y,Scott A,Wild CJ

更新日期：2009-01-30 00:00:00

abstract：:Genetic networks for gene expression data are often built by graphical models, which in turn are built from pair-wise correlations of gene expression levels. A key feature of building graphical models is the evaluation of conditional independence of two traits, given other traits. When conditional independence can be ...

journal_title：Statistics in medicine

authors： Yu Z,Wang L,Hildebrandt MA,Schaid DJ

更新日期：2008-08-30 00:00:00

abstract：:Teaching statistics to medical students is a challenging and often unrewarding task. However, few would argue the need for statistics in the medical school curriculum. In recent years, there has been a growing call for teaching only statistical concepts in medical schools. We strongly oppose this opinion and offer an ...

journal_title：Statistics in medicine

authors： Herman A,Notzer N,Libman Z,Braunstein R,Steinberg DM

更新日期：2007-10-15 00:00:00

abstract：:This paper gives a standard error for Cohen's Kappa, conditional on the margins of the observed r x r table. An explicit formula is given for the 2 x 2 table, and a procedure for the more general situation. A parsimonious log-linear model is suggested for the general case and an approximate confidence interval for kap...

journal_title：Statistics in medicine

authors： Garner JB

更新日期：1991-05-01 00:00:00

abstract：:Within the rich literature on generalized linear models, substantial efforts have been devoted to models for categorical responses that are either completely ordered or completely unordered. Few studies have focused on the analysis of partially ordered outcomes, which arise in practically every area of study, includin...

journal_title：Statistics in medicine

authors： Zhang Q,Ip EH

更新日期：2012-01-13 00:00:00

abstract：:This work is motivated by a longitudinal study of women and their ectopic pregnancy outcomes in Lund, Sweden. In this article, we review and apply the Liang-Zeger methodology to the Lund ectopic pregnancy data set. We further analyse the ectopic pregnancy data using conditional modelling approaches suggested by Rosner...

journal_title：Statistics in medicine

authors： Hadgu A,Koch G,Westrom L

更新日期：1997-11-15 00:00:00

abstract：:The design of a cross-sectional survey to estimate the age-specific incidence of an irreversible disease is considered, where the incidence rate is not changing over time and the risk of mortality is not affected by the onset of disease. The sample is assumed to give information on the current age and disease status o...

journal_title：Statistics in medicine

authors： Marschner IC

更新日期：1994-11-30 00:00:00

abstract：:The objective of a phase II cancer clinical trial is to screen a treatment that can produce a similar or better response rate compared to the current treatment results. This screening is usually carried out in two stages as proposed by Simon. For ineffective treatment, the trial should terminate at the first stage. En...

journal_title：Statistics in medicine

authors： Chen TT

更新日期：1997-12-15 00:00:00

abstract：:Lower urinary tract symptoms can indicate the presence of urinary tract infection (UTI), a condition that if it becomes chronic requires expensive and time consuming care as well as leading to reduced quality of life. Detecting the presence and gravity of an infection from the earliest symptoms is then highly valuable...

journal_title：Statistics in medicine

authors： Barcella W,Iorio MD,Baio G,Malone-Lee J

更新日期：2016-04-15 00:00:00

abstract：:Pattern-mixture models (PMM) and selection models (SM) are alternative approaches for statistical analysis when faced with incomplete data and a nonignorable missing-data mechanism. Both models make empirically unverifiable assumptions and need additional constraints to identify the parameters. Here, we first introduc...

journal_title：Statistics in medicine

authors： Kaciroti NA,Raghunathan T

更新日期：2014-11-30 00:00:00

abstract：:Optimal prevention and treatment strategies for a disease of multiple causes, such as pneumonia, must be informed by the population distribution of causes among cases, or cause-specific case fractions (CSCFs). CSCFs may further depend on additional explanatory variables. Existing methodological literature in disease e...

journal_title：Statistics in medicine

authors： Wu Z,Chen I

更新日期：2021-02-20 00:00:00

abstract：:The application of Bayesian hierarchical models to measure spatial effects in time to event data has not been widely reported. This case study aims to estimate the effect of area of residence on waiting times to coronary artery bypass graft (CABG) and to assess the role of important individual specific covariates (age...

journal_title：Statistics in medicine

authors： Crook AM,Knorr-Held L,Hemingway H

更新日期：2003-09-30 00:00:00

abstract：:Statistical inference based on correlated count measurements are frequently performed in biomedical studies. Most of existing sample size calculation methods for count outcomes are developed under the Poisson model. Deviation from the Poisson assumption (equality of mean and variance) has been widely documented in pra...

journal_title：Statistics in medicine

authors： Li D,Zhang S,Cao J

更新日期：2019-12-10 00:00:00

abstract：:Surrogate endpoint validation has been well established by the meta-analytical correlation-based approach as outlined in the seminal work of Buyse et al. (Biostatistics, 2000). Surrogacy can be assumed if strong associations on individual and study levels can be demonstrated. Alternatively, if an effect on a true endp...

journal_title：Statistics in medicine

authors： Schürmann C,Sieben W

更新日期：2016-03-30 00:00:00

abstract：:Frequently, multiple doses of an active treatment and multiple endpoints are simultaneously considered in the designs of clinical trials. For these trials, traditional multiplicity adjustment procedures such as Bonferroni, Hochberg and Hommel procedures can be applied when treating the comparisons of different doses t...

journal_title：Statistics in medicine

authors： Quan H,Luo X,Capizzi T

更新日期：2005-07-30 00:00:00