Statistical inferences for a twin correlation with multinomial outcomes.

abstract：:Clinical trials of treatments for rare or fatal diseases must often use historical rather than randomized concurrent controls. Randomized trials may not be possible if (1) the number of patients available is quite small, (2) ethical considerations discourage the assignment of patients to control treatments known to be...

journal_title：Statistics in medicine

authors： Hoehler FK,Mantel N,Gehan E,Kahana E,Alter M

更新日期：1984-07-01 00:00:00

abstract：:In many biomedical and epidemiological studies, data are often clustered due to longitudinal follow up or repeated sampling. While in some clustered data the cluster size is pre-determined, in others it may be correlated with the outcome of subunits, resulting in informative cluster size. When the cluster size is info...

journal_title：Statistics in medicine

authors： Chen Z,Zhang B,Albert PS

更新日期：2011-07-10 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：:We analyze data obtained from a study designed to evaluate training effects on the performance of certain motor activities of Parkinson's disease patients. Maximum likelihood methods were used to fit beta-binomial/Poisson regression models tailored to evaluate the effects of training on the numbers of attempted and su...

journal_title：Statistics in medicine

authors： Lora MI,Singer JM

更新日期：2008-07-30 00:00:00

abstract：:The goal of phase I cancer trials is to determine the highest dose of a treatment regimen with an acceptable toxicity rate. Traditional designs for phase I trials, such as the Continual Reassessment Method (CRM) and the 3 + 3 design, require each patient or a cohort of patients to be fully evaluated for the dose-limit...

journal_title：Statistics in medicine

authors： Polley MY

更新日期：2011-07-30 00:00:00

abstract：:Adaptive designs have been proposed for clinical trials in which the nuisance parameters or alternative of interest are unknown or likely to be misspecified before the trial. Although most previous works on adaptive designs and mid-course sample size re-estimation have focused on two-stage or group-sequential designs ...

journal_title：Statistics in medicine

authors： Bartroff J,Lai TL

更新日期：2008-05-10 00:00:00

abstract：:Observational studies provide a rich source of information for assessing effectiveness of treatment interventions in many situations where it is not ethical or practical to perform randomized controlled trials. However, such studies are prone to bias from hidden (unmeasured) confounding. A promising approach to identi...

journal_title：Statistics in medicine

authors： Lin NX,Henley WE

更新日期：2016-12-10 00:00:00

abstract：:We consider the problem of identifying subgroups of participants in a clinical trial that have enhanced treatment effect. Recursive partitioning methods that recursively partition the covariate space based on some measure of between groups treatment effect difference are popular for such subgroup identification. The m...

journal_title：Statistics in medicine

authors： Steingrimsson JA,Yang J

更新日期：2019-09-20 00:00:00

abstract：:The power prior has been widely used in many applications covering a large number of disciplines. The power prior is intended to be an informative prior constructed from historical data. It has been used in clinical trials, genetics, health care, psychology, environmental health, engineering, economics, and business. ...

journal_title：Statistics in medicine

authors： Ibrahim JG,Chen MH,Gwon Y,Chen F

更新日期：2015-12-10 00:00:00

abstract：:In the analysis of survival data, there are often competing events that preclude an event of interest from occurring. Regression analysis with competing risks is typically undertaken using a cause-specific proportional hazards model. However, modern alternative methods exist for the analysis of the subdistribution haz...

journal_title：Statistics in medicine

authors： Lau B,Cole SR,Gange SJ

更新日期：2011-03-15 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：:Longitudinal studies collect information on a sample of individuals which is followed over time to analyze the effects of individual and time-dependent characteristics on the observed response. These studies often suffer from attrition: individuals drop out of the study before its completion time and thus present inco...

journal_title：Statistics in medicine

authors： Alfò M,Maruotti A

更新日期：2009-08-30 00:00:00

abstract：:Clinical trials utilizing predictive biomarkers have become a research focus in personalized medicine. We investigate the effects of biomarker misclassification on the design and analysis of stratified biomarker clinical trials. For a variety of inference problems including marker-treatment interaction in particular, ...

journal_title：Statistics in medicine

authors： Liu C,Liu A,Hu J,Yuan V,Halabi S

更新日期：2014-08-15 00:00:00

abstract：:We propose a goodness-of-fit test statistic for linear regression with heterogeneous variance, which is asymptotically chi-square if the given model is correct. The test statistic is computed as a quadratic form of observed minus predicted responses. We apply the method to a linear regression for an ordinal categorica...

journal_title：Statistics in medicine

authors： Lipsitz SR,Buoncristiani JF

更新日期：1994-01-30 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：:We examine the properties of several tests for goodness-of-fit for multinomial logistic regression. One test is based on a strategy of sorting the observations according to the complement of the estimated probability for the reference outcome category and then grouping the subjects into g equal-sized groups. A g x c c...

journal_title：Statistics in medicine

authors： Fagerland MW,Hosmer DW,Bofin AM

更新日期：2008-09-20 00:00:00

abstract：:We examine the common clinical belief that there is an interaction between epilepsy type and the two standard anti-epileptic drugs, valproate and carbamazepine, using data from several randomized clinical trials. Epilepsy type is not always easy to define, and three possible reclassifications are investigated to see w...

journal_title：Statistics in medicine

authors： Williamson PR,Clough HE,Hutton JL,Marson AG,Chadwick DW

更新日期：2002-09-30 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：:An important problem in oncology is comparing chemotherapy (chemo) agents in terms of their effects on survival or progression-free survival time. When the goal is to evaluate individual agents, a difficulty commonly encountered with observational data is that many patients receive a chemo combination including two or...

journal_title：Statistics in medicine

authors： Thall PF,Liu DD,Berrak SG,Wolff JE

更新日期：2011-07-10 00:00:00

abstract：:Identification of treatment selection biomarkers has become very important in cancer drug development. Adaptive enrichment designs have been developed for situations where a unique treatment selection biomarker is not apparent based on the mechanism of action of the drug. With such designs, the eligibility rules may b...

journal_title：Statistics in medicine

authors： Simon R,Simon N

更新日期：2017-11-20 00:00:00

abstract：:Composite endpoints are frequently used in clinical trials, but simple approaches, such as the time to first event, do not reflect any ordering among the endpoints. However, some endpoints, such as mortality, are worse than others. A variety of procedures have been proposed to reflect the severity of the individual en...

journal_title：Statistics in medicine

authors： Follmann D,Fay MP,Hamasaki T,Evans S

更新日期：2020-02-28 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：:Wittes and Brittain recommended using an 'internal pilot study' to adjust sample size. The approach involves five steps in testing a general linear hypothesis for a general linear univariate model, with Gaussian errors. First, specify the design, hypothesis, desired test size, power, a smallest 'clinically meaningful'...

journal_title：Statistics in medicine

authors： Coffey CS,Muller KE

更新日期：1999-05-30 00:00:00

abstract：:Prognostic models are used in medicine for investigating patient outcome in relation to patient and disease characteristics. Such models do not always work well in practice, so it is widely recommended that they need to be validated. The idea of validating a prognostic model is generally taken to mean establishing tha...

journal_title：Statistics in medicine

authors： Altman DG,Royston P

更新日期：2000-02-29 00:00:00

abstract：:Often multiple outcomes are of interest in each study identified by a systematic review, and in this situation a separate univariate meta-analysis is usually applied to synthesize the evidence for each outcome independently; an alternative approach is a single multivariate meta-analysis model that utilizes any correla...

journal_title：Statistics in medicine

authors： Riley RD,Abrams KR,Lambert PC,Sutton AJ,Thompson JR

更新日期：2007-01-15 00:00:00

abstract：:Effective statistical help to biological and medical research demands thorough involvement of the statistician. The breadth of his activities can be illustrated by considering the questions he needs to discuss with his scientific colleagues in the course of planning a comparative experiment. The paper presents and com...

journal_title：Statistics in medicine

authors： Finney DJ

更新日期：1982-01-01 00:00:00

abstract：:In comparing two treatments under a typical sequential clinical trial setting, a 50-50 randomization design generates reliable data for making efficient inferences about the treatment difference for the benefit of patients in the general population. However, if the treatment difference is large and the endpoint of the...

journal_title：Statistics in medicine

authors： Yao Q,Wei LJ

更新日期：1996-11-15 00:00:00

abstract：:In repeated measures settings, modeling the correlation pattern of the data can be immensely important for proper analyses. Accurate inference requires proper choice of the correlation model. Optimal efficiency of the estimation procedure demands a parsimonious parameterization of the correlation structure, with suffi...

journal_title：Statistics in medicine

authors： Simpson SL,Edwards LJ,Muller KE,Sen PK,Styner MA

更新日期：2010-07-30 00:00:00

abstract：:Generalized linear models are often assumed to fit propensity scores, which are used to compute inverse probability weighted (IPW) estimators. To derive the asymptotic properties of IPW estimators, the propensity score is supposed to be bounded away from zero. This condition is known in the literature as strict positi...

journal_title：Statistics in medicine

authors： Molina J,Sued M,Valdora M

更新日期：2018-10-30 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