Effects of time-invariant covariates on the estimation of longitudinal trends for transition mixed models.

abstract：:Ordinal data appear in a wide variety of scientific fields. These data are often analyzed using ordinal logistic regression models that assume proportional odds. When this assumption is not met, it may be possible to capture the lack of proportionality using a constrained structural relationship between the odds and t...

journal_title：Statistics in medicine

authors： Capuano AW,Dawson JD

更新日期：2013-06-15 00:00:00

abstract：:Systematic reviews often provide recommendations for further research. When meta-analyses are inconclusive, such recommendations typically argue for further studies to be conducted. However, the nature and amount of future research should depend on the nature and amount of the existing research. We propose a method ba...

journal_title：Statistics in medicine

authors： Roloff V,Higgins JP,Sutton AJ

更新日期：2013-01-15 00:00:00

abstract：:Most statistical methodology for phase III clinical trials focuses on the comparison of a single experimental treatment with a control. An increasing desire to reduce the time before regulatory approval of a new drug is sought has led to development of two-stage or sequential designs for trials that combine the defini...

journal_title：Statistics in medicine

authors： Stallard N,Todd S

更新日期：2003-03-15 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：: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：: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：:We consider statistical procedures for hypothesis testing of real valued functionals of matched pairs with missing values. In order to improve the accuracy of existing methods, we propose a novel multiplication combination procedure. Dividing the observed data into dependent (completely observed) pairs and independent...

journal_title：Statistics in medicine

authors： Amro L,Konietschke F,Pauly M

更新日期：2019-07-30 00:00:00

abstract：:An observed confidence distribution is proposed as a measure of strength of evidence for practically equivalent efficacies of two treatments. The concept is independent of prior opinions about relevant sizes of a difference in efficacy. It also avoids retrospective power calculations for trials with missed recruitment...

journal_title：Statistics in medicine

authors： Mau J

更新日期：1988-12-01 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：:Statistical modeling methods have had increasing use in drug disposition studies, both to estimate pharmacokinetic parameters and to develop regression models that relate these parameter estimates to patient characteristics. These methods are particularly flexible as they allow non-linearity and sparse within-patient ...

journal_title：Statistics in medicine

authors： Roe DJ

更新日期：1997-06-15 00:00:00

abstract：:A mixed effect model is proposed to jointly analyze multivariate longitudinal data with continuous, proportion, count, and binary responses. The association of the variables is modeled through the correlation of random effects. We use a quasi-likelihood type approximation for nonlinear variables and transform the prop...

journal_title：Statistics in medicine

authors： Li H,Zhang Y,Carroll RJ,Keadle SK,Sampson JN,Matthews CE

更新日期：2017-11-10 00:00:00

abstract：:Health questionnaires are often built up from sets of questions that are totaled to obtain a sum score. An important consideration in designing questionnaires is to minimize respondent burden. An increasingly popular method for efficient measurement is computerized adaptive testing; unfortunately, many health question...

journal_title：Statistics in medicine

authors： Smits N,Finkelman MD

更新日期：2014-02-10 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：:There has been substantial statistical literature in the last several decades on assessing agreement, and coverage probability approach was selected as a preferred index for assessing and improving measurement agreement in a core laboratory setting. With this approach, a satisfactory agreement is based on pre-specifie...

journal_title：Statistics in medicine

authors： Barnhart HX

更新日期：2016-08-15 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：:The 'landmark' and 'Simon and Makuch' non-parametric estimators of the survival function are commonly used to contrast the survival experience of time-dependent treatment groups in applications such as stem cell transplant versus chemotherapy in leukemia. However, the theoretical survival functions corresponding to th...

journal_title：Statistics in medicine

authors： Bernasconi DP,Rebora P,Iacobelli S,Valsecchi MG,Antolini L

更新日期：2016-03-30 00:00:00

abstract：:A trial of Duchenne muscular dystrophy involved tracking boys of all ages through a one-year baseline period, followed by a one-year trial of leucine versus placebo treatment. In this paper we develop a model for a total-muscle-strength score that uses the data of the extended baseline period in the evaluation of the ...

journal_title：Statistics in medicine

authors： Madsen KS,Miller JP,Province MA

更新日期：1986-05-01 00:00:00

abstract：:The use of outcome-dependent sampling with longitudinal data analysis has previously been shown to improve efficiency in the estimation of regression parameters. The motivating scenario is when outcome data exist for all cohort members but key exposure variables will be gathered only on a subset. Inference with outcom...

journal_title：Statistics in medicine

authors： Zelnick LR,Schildcrout JS,Heagerty PJ

更新日期：2018-06-15 00:00:00

abstract：:Relative survival is used to estimate patient survival excluding causes of death not related to the disease of interest. Rather than using cause of death information from death certificates, which is often poorly recorded, relative survival compares the observed survival to that expected in a matched group from the ge...

journal_title：Statistics in medicine

authors： Lambert PC,Smith LK,Jones DR,Botha JL

更新日期：2005-12-30 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：:The randomized clinical trial, LU19, conducted by the Medical Research Council Lung Cancer Working Party, was designed to compare ACE (doxorubicin, cyclophosphamide and etoposide) chemotherapy plus G-CSF (granulocyte colony-stimulating factor) at 2-week intervals versus ACE chemotherapy alone at standard 3-week interv...

journal_title：Statistics in medicine

authors： Qian W,Parmar MK,Sambrook RJ,Fayers PM,Girling DJ,Stephens RJ

更新日期：2000-10-15 00:00:00

abstract：:Equal allocation of patients to treatment in a randomized clinical trial may have disadvantages ethically if the new treatment is believed to be at least as beneficial as the standard treatment. Others have considered, in a non-sequential setting, unbalanced randomized designs which allocate fewer patients to the pote...

journal_title：Statistics in medicine

authors： Lesser ML

更新日期：1982-07-01 00:00:00

abstract：:Confidence intervals for a standardized effect are derived after stabilizing the variance of the Welch t-statistic. Simulation studies demonstrate the viability of the resulting intervals for a wide range of parameter values and sample sizes as small as five. The methodology is extended to the combination of results f...

journal_title：Statistics in medicine

authors： Kulinskaya E,Staudte RG

更新日期：2007-06-30 00:00:00

abstract：:In any field in which decisions are subject to measurements, interchangeability between the methods used to obtain these measurements is essential. To consider methods as interchangeable, a certain degree of agreement is needed between the measurements they provide. The concordance correlation coefficient is an index ...

journal_title：Statistics in medicine

authors： Carrasco JL,Jover L

更新日期：2005-12-30 00:00:00

abstract：:Recent studies have indicated variation in the infectivity beta of HIV among heterosexual couples. We represent this heterogeneity by modelling beta as a random variable. Using data on the number of contacts and seroconversion of couples, we fit the model by maximum-likelihood estimation with a beta distribution and a...

journal_title：Statistics in medicine

authors： Wiley JA,Herschkorn SJ,Padian NS

更新日期：1989-01-01 00:00:00

abstract：:Cancer immunotherapy trials have two special features: a delayed treatment effect and a cure rate. Both features violate the proportional hazard model assumption and ignoring either one of the two features in an immunotherapy trial design will result in substantial loss of statistical power. To properly design immunot...

journal_title：Statistics in medicine

authors： Wei J,Wu J

更新日期：2020-03-15 00:00:00

abstract：:Generalized relative and absolute risk models, in which various functions of time and age modify the excess relative or absolute risk of radiation-induced cancer, are fitted to the Japanese atomic bomb survivor cancer incidence data set. Among generalized relative risk models, those in which a product of powers of tim...

journal_title：Statistics in medicine

authors： Little MP,Muirhead CR,Charles MW

更新日期：1999-01-15 00:00:00

abstract：:Meta analysis is a collection of quantitative methods devoted to combine summary information from related but independent studies. Because research reports usually present only data reductions and summary statistics rather than detailed data, the reviewer must often resort to rather crude methods for constructing summ...

journal_title：Statistics in medicine

authors： Di Pietrantonj C

更新日期：2006-07-15 00:00:00

abstract：:A calibration line is used to define the relationship between a new clinical technique and a standard in vitro laboratory methodology. Discrimination intervals quantify the reliability of inverse estimates obtained from the calibration line. Applied to transcutaneous PCO2 monitoring, a new in vivo measurement, discrim...

journal_title：Statistics in medicine

authors： Kost GJ

更新日期：1986-07-01 00:00:00

abstract：:In randomised trials, continuous endpoints are often measured with some degree of error. This study explores the impact of ignoring measurement error and proposes methods to improve statistical inference in the presence of measurement error. Three main types of measurement error in continuous endpoints are considered:...

journal_title：Statistics in medicine

authors： Nab L,Groenwold RHH,Welsing PMJ,van Smeden M

更新日期：2019-11-30 00:00:00