Concordance correlation coefficient applied to discrete data.

abstract：:In clinical research, we are often interested in assessing how a biomarker changes with time, and whether it could be used as a surrogate marker when evaluating the efficacy of a new drug. However, when the longitudinal marker is correlated with survival, linear mixed models for longitudinal data may be inappropriate....

journal_title：Statistics in medicine

authors： Deslandes E,Chevret S

更新日期：2007-12-30 00:00:00

abstract：:Although estimation and confidence intervals have become popular alternatives to hypothesis testing and p-values, statisticians usually determine sample sizes for randomized clinical trials by controlling the power of a statistical test at an appropriate alternative, even those statisticians who recommend the use of c...

journal_title：Statistics in medicine

authors： Bristol DR

更新日期：1989-07-01 00:00:00

abstract：:This paper introduces a new spatial scan statistic designed to adjust cluster detection for longitudinal confounding factors indexed in space. The functional-model-adjusted statistic was developed using generalized functional linear models in which longitudinal confounding factors were considered to be functional cova...

journal_title：Statistics in medicine

authors： Ahmed MS,Genin M

更新日期：2020-04-15 00:00:00

abstract：:Epidermal nerve fibre (ENF) density and morphology are used to study small fibre involvement in diabetic, HIV, chemotherapy induced and other neuropathies. ENF density and summed length of ENFs per epidermal surface area are reduced, and ENFs may appear more clustered within the epidermis in subjects with small fibre ...

journal_title：Statistics in medicine

authors： Andersson C,Guttorp P,Särkkä A

更新日期：2016-10-30 00:00:00

abstract：:We present graphical and numerical methods for assessing the adequacy of the logistic regression model for stratified case-control data. The proposed methods are derived from the cumulative sum of residuals over the covariate or linear predictor. Under the assumed model, the cumulative residual process converges weakl...

journal_title：Statistics in medicine

authors： Arbogast PG,Lin DY

更新日期：2005-01-30 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：:The change in c-statistic is frequently used to summarize the change in predictive accuracy when a novel risk factor is added to an existing logistic regression model. We explored the relationship between the absolute change in the c-statistic, Brier score, generalized R(2) , and the discrimination slope when a risk f...

journal_title：Statistics in medicine

authors： Austin PC,Steyerberg EW

更新日期：2013-02-20 00:00:00

abstract：:In natural history studies of chronic disease, it is of interest to understand the evolution of key variables that measure aspects of disease progression. This is particularly true for immunological variables among persons infected with the human immunodeficiency virus (HIV). The natural time scale for such studies is...

journal_title：Statistics in medicine

authors： Vittinghoff E,Malani HM,Jewell NP

更新日期：1994-06-15 00:00:00

abstract：:Methods for addressing multiplicity in clinical trials have attracted much attention during the past 20 years. They include the investigation of new classes of multiple test procedures, such as fixed sequence, fallback and gatekeeping procedures. More recently, sequentially rejective graphical test procedures have bee...

journal_title：Statistics in medicine

authors： Maurer W,Bretz F

更新日期：2013-05-10 00:00:00

abstract：:Piecewise constant incidence models were developed to estimate the force of infection in women from age- and time-specific antenatal or neonatal seroprevalence data. Differential inclusion of infected women in sero-surveys compared to uninfected women was taken into account, with respect to both changes in inclusion r...

journal_title：Statistics in medicine

authors： Ades AE,Medley GF

更新日期：1994-09-30 00:00:00

abstract：:Interim analyses are conducted to allow for early termination of the trial, for ethical as well as economical reasons. Here we consider interim analyses in repeated measurements studies where the measurements are binary. Two methods for analysing this kind of data are compared according to their operating characterist...

journal_title：Statistics in medicine

authors： Spiessens B,Lesaffre E,Verbeke G

更新日期：2003-02-28 00:00:00

abstract：:Treatment effects for multiple outcomes can be meta-analyzed separately or jointly, but no systematic empirical comparison of the two approaches exists. From the Cochrane Library of Systematic Reviews, we identified 45 reviews, including 1473 trials and 258,675 patients, that contained two or three univariate meta-ana...

journal_title：Statistics in medicine

authors： Trikalinos TA,Hoaglin DC,Schmid CH

更新日期：2014-04-30 00:00:00

abstract：:We propose a new weighted hurdle regression method for modeling count data, with particular interest in modeling cardiovascular events in patients on dialysis. Cardiovascular disease remains one of the leading causes of hospitalization and death in this population. Our aim is to jointly model the relationship/associat...

journal_title：Statistics in medicine

authors： Sentürk D,Dalrymple LS,Mu Y,Nguyen DV

更新日期：2014-11-10 00:00:00

abstract：:Many observational studies adopt what we call retrospective convenience sampling (RCS). With the sample size in each arm prespecified, RCS randomly selects subjects from the treatment-inclined subpopulation into the treatment arm and those from the control-inclined into the control arm. Samples in each arm are represe...

journal_title：Statistics in medicine

authors： Hu Z,Qin J

更新日期：2018-05-20 00:00:00

abstract：:Suppression of premature ventricular contractions (PVCs) is one of the goals of antiarrhythmic therapy. In a clinical trial, however, it may be difficult to distinguish antiarrhythmic drug effect from spontaneous variation in PVCs. We propose the application of linear regression to PVC histories to ascertain drug effe...

journal_title：Statistics in medicine

authors： Berry DA,Fox TL

更新日期：1983-07-01 00:00:00

abstract：:Quantifying socioeconomic disparities and understanding the roots of inequalities are growing topics in cancer research. However, socioeconomic differences are challenging to investigate mainly due to the lack of accurate data at individual-level, while aggregate indicators are only partially informative. We implement...

journal_title：Statistics in medicine

authors： Mezzetti M,Palli D,Dominici F

更新日期：2020-01-15 00:00:00

abstract：:Appropriate quantification of added usefulness offered by new markers included in risk prediction algorithms is a problem of active research and debate. Standard methods, including statistical significance and c statistic are useful but not sufficient. Net reclassification improvement (NRI) offers a simple intuitive w...

journal_title：Statistics in medicine

authors： Pencina MJ,D'Agostino RB Sr,Steyerberg EW

更新日期：2011-01-15 00:00:00

abstract：:Dependence between observations on a dichotomous variable renders invalid the usual chi-square tests of independence and inflates the variances of parameter estimates. Such a situation occurs, for example, when subjects consist of members of the same family or with repeated observations on the same person. In this pap...

journal_title：Statistics in medicine

authors： Donald A,Donner A

更新日期：1987-06-01 00:00:00

abstract：:The receiver operating characteristic (ROC) curve can be utilized to evaluate the performance of diagnostic tests. The area under the ROC curve (AUC) is a widely used summary index for comparing multiple ROC curves. Both parametric and nonparametric methods have been developed to estimate and compare the AUCs. However...

journal_title：Statistics in medicine

authors： Yao W,Li Z,Graubard BI

更新日期：2015-04-15 00:00:00

abstract：:We propose a two-step procedure to personalize drug dosage over time under the framework of a log-linear mixed-effect model. We model patients' heterogeneity using subject-specific random effects, which are treated as the realizations of an unspecified stochastic process. We extend the conditional quadratic inference ...

journal_title：Statistics in medicine

authors： Zhu X,Qu A

更新日期：2016-10-30 00:00:00

abstract：:This paper considers the regression analysis of CD4 cell counts, a commonly used indicator and prognostic factor of AIDS progression. For this purpose, a number of methods have been proposed and most of them are based on random effects models. We present an alternative that is based on a mean function regression model...

journal_title：Statistics in medicine

authors： Sun J

更新日期：2001-11-15 00:00:00

abstract：:Patient non-compliance and drop-out can bias analyses of clinical trial data. I describe a parametric model for treatment cross-over and drop-out and demonstrate how the concept of ignorability, originally defined for incomplete-data problems, can elucidate sources of bias in clinical trials. I discuss some implicatio...

journal_title：Statistics in medicine

authors： Heitjan DF

更新日期：1999-09-15 00:00:00

abstract：:We use a mixed Poisson regression model with extra variation to analyse mortality data cross-classified by age and geographic region. We use estimates of dispersion parameter and fixed effects parameters, obtained by maximizing a marginal quasi-likelihood function, to estimate mortality rates in an empirical Bayes man...

journal_title：Statistics in medicine

authors： Lu WS,Tsutakawa RK

更新日期：1996-07-15 00:00:00

abstract：:In many chronic disease processes subjects are at risk of two or more types of events. We describe a bivariate mixed Poisson model in which a copula function is used to model the association between two gamma distributed random effects. The resulting model is a bivariate negative binomial process in which each type of...

journal_title：Statistics in medicine

authors： Cook RJ,Lawless JF,Lee KA

更新日期：2010-03-15 00:00:00

abstract：:Lung function tests are used both clinically, in assessing disease, and epidemiologically, in identifying those factors which influence the growth and aging process of the lungs. The user must beware of several common pitfalls in the use of these tests, however. First, the commonly used tests of lung function can only...

journal_title：Statistics in medicine

authors： Buist AS,Vollmer WM

更新日期：1988-01-01 00:00:00

abstract：:In recent years, follow-on biological products (biosimilars) have received much attention from both the biotechnology industry and the regulatory agencies, especially after the passage of the 2010 healthcare reform bill. Unlike the traditional small-molecule drug products, the development of biological products is not...

journal_title：Statistics in medicine

authors： Yang J,Zhang N,Chow SC,Chi E

更新日期：2013-02-10 00:00:00

abstract：:In conventional survival analysis there is an underlying assumption that all study subjects are susceptible to the event. In general, this assumption does not adequately hold when investigating the time to an event other than death. Owing to genetic and/or environmental etiology, study subjects may not be susceptible ...

journal_title：Statistics in medicine

authors： Chen CH,Tsay YC,Wu YC,Horng CF

更新日期：2013-10-30 00:00:00

abstract：:Many gene expression data are based on two experiments where the gene expressions of the targeted genes under both experiments are correlated. We consider problems in which objectives are to find genes that are simultaneously upregulated/downregulated under both experiments. A Bayesian methodology is proposed based on...

journal_title：Statistics in medicine

authors： Bansal NK,Jiang H,Pradeep P

更新日期：2015-11-10 00:00:00

abstract：:In survival analyses, inverse-probability-of-treatment (IPT) and inverse-probability-of-censoring (IPC) weighted estimators of parameters in marginal structural Cox models are often used to estimate treatment effects in the presence of time-dependent confounding and censoring. In most applications, a robust variance e...

journal_title：Statistics in medicine

authors： Enders D,Engel S,Linder R,Pigeot I

更新日期：2018-10-30 00:00:00

abstract：:The problem of evaluating an averaged functional magnetic resonance imaging (fMRI) response for repeated block design experiments was considered within a semiparametric regression model with autocorrelated residuals. We applied functional data analysis (FDA) techniques that use a least-squares fitting of B-spline expa...

journal_title：Statistics in medicine

authors： Vakorin VA,Borowsky R,Sarty GE

更新日期：2007-09-20 00:00:00