Construction, validation and updating of a prognostic model for kidney graft survival.

abstract：:Variation in heart disease (HD) mortality rates across census tracts is greater than expected given binomial error and available explanatory variables. We extended an extra-binomial variation model for rates standardized by the direct method. The overdispersion parameter accounted for 36 per cent of the observed varia...

journal_title：Statistics in medicine

authors： Jarjoura D,Logue E

更新日期：1990-10-01 00:00:00

abstract：:A statistical definition of surrogate endpoints as well as validation criteria was first presented by Prentice. Freedman et al. supplemented these criteria with the so-called proportion explained. Buyse and Molenberghs pointed to inadequacies of these criteria and suggested a new definition of surrogacy based on (i) t...

journal_title：Statistics in medicine

authors： Molenberghs G,Geys H,Buyse M

更新日期：2001-10-30 00:00:00

abstract：:The treatment effect sizes that can be detected with sufficient power up to the different interim analyses constitute a clinically meaningful criterion for the selection of a group sequential test for a clinical trial. For any pre-specified sequence of effect sizes, it is possible to construct group sequential boundar...

journal_title：Statistics in medicine

authors： Schäfer H,Müller HH

更新日期：2004-05-15 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：: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：: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：:It is well established that neural activity is stochastically modulated over time. Therefore, direct comparisons across experimental conditions and determination of change points or maximum firing rates are not straightforward. This study sought to compare temporal firing probability curves that may vary across groups...

journal_title：Statistics in medicine

authors： Roca-Pardiñas J,Cadarso-Suárez C,Pardo-Vazquez JL,Leboran V,Molenberghs G,Faes C,Acuña C

更新日期：2011-06-30 00:00:00

abstract：:This paper presents a mixture model which combines features of the usual Cox proportional hazards model with those of a class of models, known as mixtures-of-experts. The resulting model is more flexible than the usual Cox model in the sense that the log hazard ratio is allowed to vary non-linearly as a function of th...

journal_title：Statistics in medicine

authors： Rosen O,Tanner M

更新日期：1999-05-15 00:00:00

abstract：:The goal of screening programmes for cancer is early detection and treatment with a consequent reduction in mortality from the disease. Screening programmes need to assess the true benefit of screening, that is, the length of time of extension of survival beyond the time of advancement of diagnosis (lead-time). This p...

journal_title：Statistics in medicine

authors： Xu JL,Prorok PC

更新日期：1995-12-30 00:00:00

abstract：:Combining multiple markers can improve classification accuracy compared with using a single marker. In practice, covariates associated with markers or disease outcome can affect the performance of a biomarker or biomarker combination in the population. The covariate-adjusted receiver operating characteristic (ROC) cur...

journal_title：Statistics in medicine

authors： Kim S,Huang Y

更新日期：2017-07-10 00:00:00

abstract：:In this paper, we consider pooling schemes in which samples are to be tested in two-stages. We show that when batch size is limited as well as pool size, selection schemes tend to be more efficient and flexible. Formulae for the efficiencies of square arrays in all dimensions and for all selection schemes are given in...

journal_title：Statistics in medicine

authors： Sudbury A

更新日期：2010-09-20 00:00:00

abstract：:In medical and health studies, heterogeneities in clustered count data have been traditionally modeled by positive random effects in Poisson mixed models; however, excessive zeros often occur in clustered medical and health count data. In this paper, we consider a three-level random effects zero-inflated Poisson model...

journal_title：Statistics in medicine

authors： Ma R,Hasan MT,Sneddon G

更新日期：2009-08-15 00:00:00

abstract：:The two-period cross-over design with two sequences of drug administration is a standard experimental design when bioequivalence of one test formulation is to be assessed in comparison with a reference formulation. Previously, an approach based on Fieller's confidence interval has been presented for the assessment of ...

journal_title：Statistics in medicine

authors： Vuorinen J

更新日期：1997-10-15 00:00:00

abstract：:In many practical applications, count data often exhibit greater or less variability than allowed by the equality of mean and variance, referred to as overdispersion/underdispersion, and there are several reasons that may lead to the overdispersion/underdispersion such as zero inflation and mixture. Moreover, if the c...

journal_title：Statistics in medicine

authors： Chen XD,Fu YZ,Wang XR

更新日期：2013-04-15 00:00:00

abstract：:This paper concerns using modified weighted Schoenfeld residuals to test the proportionality of subdistribution hazards for the Fine-Gray model, similar to the tests proposed by Grambsch and Therneau for independently censored data. We develop a score test for the time-varying coefficients based on the modified Schoen...

journal_title：Statistics in medicine

authors： Zhou B,Fine J,Laird G

更新日期：2013-09-30 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：:Regression to the mean arises often in statistical applications where the units chosen for study relate to some observed characteristic in the extreme of its distribution. Gardner and Heady attribute the effect of regression to the mean to measurement errors. They assume the model Yi = U + ei, where U is a fixed withi...

journal_title：Statistics in medicine

authors： Johnson WD,George VT

更新日期：1991-08-01 00:00:00

abstract：:The use of classification and regression tree (CART) methodology is explored for the diagnosis of patients complaining of anterior chest pain. The results are compared with those previously obtained using correspondence analysis and independent Bayes classification. The technique is shown to be of potential value for ...

journal_title：Statistics in medicine

authors： Crichton NJ,Hinde JP,Marchini J

更新日期：1997-04-15 00:00:00

abstract：:In this article, we investigate procedures for comparing two independent Poisson variates that are observed over unequal sampling frames (i.e. time intervals, populations, areas or any combination thereof). We consider two statistics (with and without the logarithmic transformation) for testing the equality of two Poi...

journal_title：Statistics in medicine

authors： Ng HK,Tang ML

更新日期：2005-03-30 00:00:00

abstract：:Meta-analyses of data from epidemiological studies are often based on odds ratios (ORs) or relative risks (RRs) and their 95 per cent confidence intervals (CIs) as reported by the authors. Where possible ORs, RRs and CIs should be checked against the source data. Some simple methods are presented for checking the vali...

journal_title：Statistics in medicine

authors： Lee PN

更新日期：1999-08-15 00:00:00

abstract：:Sequential analysis is frequently employed to address ethical and financial issues in clinical trials. Sequential analysis may be performed using standard group sequential designs, or, more recently, with adaptive designs that use estimates of treatment effect to modify the maximal statistical information to be collec...

journal_title：Statistics in medicine

authors： Emerson SC,Rudser KD,Emerson SS

更新日期：2011-05-20 00:00:00

abstract：:Statisticians have long argued that randomized controlled trials should be sufficiently large to achieve their purpose, and for common diseases with major public health implications this has brought many benefits. However, there are many instances where it is unrealistic to expect clinicians to provide the information...

journal_title：Statistics in medicine

authors： Matthews JN

更新日期：1995-01-30 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：: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：:Testing the equality of 2 proportions for a control group versus a treatment group is a well-researched statistical problem. In some settings, there may be strong historical data that allow one to reliably expect that the control proportion is one, or nearly so. While one-sample tests or comparisons to historical cont...

journal_title：Statistics in medicine

authors： Gabriel EE,Nason M,Fay MP,Follmann DA

更新日期：2018-03-30 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：:Prevalent sampling is frequently a convenient and economical sampling technique for the collection of time-to-event data and thus is commonly used in studies of the natural history of a disease. However, it is biased by design because it tends to recruit individuals with longer survival times. This paper considers est...

journal_title：Statistics in medicine

authors： Li S

更新日期：2017-04-15 00:00:00

abstract：:In this paper, we develop a method for the simultaneous estimation of spectral density functions (SDFs) for a collection of stationary time series that share some common features. Due to the similarities among the SDFs, the log-SDF can be represented using a common set of basis functions. The basis shared by the colle...

journal_title：Statistics in medicine

authors： Maadooliat M,Sun Y,Chen T

更新日期：2018-12-30 00:00:00

abstract：:We describe how trends in the vaccination coverage at 19 months of age vary by race/ethnicity; explore the extent to which data required to evaluate a child's up-to-date vaccination status is missing as a result of the scattering of vaccination records among many vaccination providers; evaluate how the prevalence of t...

journal_title：Statistics in medicine

authors： Smith PJ,Stevenson J

更新日期：2008-09-10 00:00:00

abstract：:The concept of broad sense agreement (BSA) has recently been proposed for studying the relationship between a continuous measurement and an ordinal measurement. They developed a nonparametric procedure for estimating the BSA index, which is only applicable to completely observed data. In this work, we consider the pro...

journal_title：Statistics in medicine

authors： Dai T,Guo Y,Peng L,Manatunga A

更新日期：2020-06-30 00:00:00