On choosing the number of interim analyses in clinical trials.

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：:A significant source of missing data in longitudinal epidemiological studies on elderly individuals is death. Subjects in large scale community-based longitudinal dementia studies are usually evaluated for disease status in study waves, not under continuous surveillance as in traditional cohort studies. Therefore, for...

journal_title：Statistics in medicine

authors： Harezlak J,Gao S,Hui SL

更新日期：2003-05-15 00:00:00

abstract：:We study the group bridge and the adaptive group bridge penalties for competing risks quantile regression with group variables. While the group bridge consistently identifies nonzero group variables, the adaptive group bridge consistently selects variables not only at group level but also at within-group level. We all...

journal_title：Statistics in medicine

authors： Ahn KW,Kim S

更新日期：2018-04-30 00:00:00

abstract：:Biostatistical concepts and methods apply to various problems arising in actual U.S. legal cases. These involve: measures of association, assessing the potential effect of omitted variables and the Peters-Belson approach to regression. In particular, we present the inapplicability of Fisher's exact test in the case wh...

journal_title：Statistics in medicine

authors： Gastwirth JL,Greenhouse SW

更新日期：1995-08-15 00:00:00

abstract：:For many HIV-infected patients, use of antiretroviral therapy (ART) results in a sustained suppression of plasma viral load to undetectable levels. However, due to lack of antigenic stimulation, this may also result in a gradual loss of cell-mediated immune (CMI) responses that help control HIV infection. In concept, ...

journal_title：Statistics in medicine

authors： Mogg R,Mehrotra DV

更新日期：2007-02-10 00:00:00

abstract：:Data on alcohol availability and problems in all cities in Los Angeles County were collected from several different sources and linked together to form a Local Alcohol Availability Database (LAAD). The two major purposes of the project are to provide a city-level alcohol availability and alcohol-related problems datab...

journal_title：Statistics in medicine

authors： MacKinnon DP,Scribner R,Taft KA

更新日期：1995-03-15 00:00:00

abstract：:We present some practical extensions and applications of a strategy proposed by Thall, Simon and Estey for designing and monitoring single-arm clinical trials with multiple outcomes. We show by application how the strategy may be applied to construct designs for phase IIA activity trials and phase II equivalence trial...

journal_title：Statistics in medicine

authors： Thall PF,Sung HG

更新日期：1998-07-30 00:00:00

abstract：:We survey models for analysing repeated observations on an ordered categorical response variable. The models presented are univariate models that permit correlation among repeated measurements. The models describe simultaneously the dependence of marginal response distributions on values of explanatory variables and o...

journal_title：Statistics in medicine

authors： Agresti A

更新日期：1989-10-01 00:00:00

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：:In psychiatry, clinicians use criteria sets from the Diagnostic and Statistical Manual of Mental Disorders to diagnose mental disorders. Most criteria sets have several symptom domains, and in order to be diagnosed, an individual must meet the minimum number of symptoms required by each domain. Some efforts are now fo...

journal_title：Statistics in medicine

authors： Mauro C,Shear MK,Wang Y

更新日期：2019-07-20 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：:The setting of a quarantine time for an emerging infectious disease will depend on current knowledge concerning incubation times. Methods for the analysis of information on incubation times are investigated with a particular focus on inference regarding a possible maximum incubation time, after which an exposed indivi...

journal_title：Statistics in medicine

authors： Farewell VT,Herzberg AM,James KW,Ho LM,Leung GM

更新日期：2005-11-30 00:00:00

abstract：:The matched case-control designs are commonly used to control for potential confounding factors in genetic epidemiology studies especially epigenetic studies with DNA methylation. Compared with unmatched case-control studies with high-dimensional genomic or epigenetic data, there have been few variable selection metho...

journal_title：Statistics in medicine

authors： Sun H,Wang S

更新日期：2013-05-30 00:00:00

abstract：:Paired count data usually arise in medicine when before and after treatment measurements are considered. In the present paper we assume that the correlated paired count data follow a bivariate Poisson distribution in order to derive the distribution of their difference. The derived distribution is shown to be the same...

journal_title：Statistics in medicine

authors： Karlis D,Ntzoufras I

更新日期：2006-06-15 00:00:00

abstract：:When sample size is recalculated using unblinded interim data, use of the usual t-test at the end of a study may lead to an elevated type I error rate. This paper describes a numerical quadrature investigation to calculate the true probability of rejection as a function of the time of the recalculation, the magnitude ...

journal_title：Statistics in medicine

authors： Wittes J,Schabenberger O,Zucker D,Brittain E,Proschan M

更新日期：1999-12-30 00:00:00

abstract：:One Sentence Summary: A Bayesian repeated measures model based on quantitative muscle strength data from a prospective Natural History Study was developed to determine disease progression and design clinical trials for GNE myopathy, a rare and slowly progressive muscle disease. GNE myopathy is a rare muscle disease ch...

journal_title：Statistics in medicine

authors： Quintana M,Shrader J,Slota C,Joe G,McKew JC,Fitzgerald M,Gahl WA,Berry S,Carrillo N

更新日期：2019-04-15 00:00:00

abstract：:Paired data from matched case-control studies are commonly used to estimate the association between the exposure to a risk factor and the occurrence of a disease. The odds ratio is typically used to quantify this association. Difficulties in estimating the true odds ratio with matched pairs arise, however, when the ex...

journal_title：Statistics in medicine

authors： Miller KM,Looney SW

更新日期：2012-11-30 00:00:00

abstract：:We extend the method proposed in a recent work by the Authors for trial-level general surrogate evaluation to allow combinations of biomarkers and provide a procedure for finding the "best" combination of biomarkers based on the absolute prediction error summary of surrogate quality. We use a nonparametric Bayesian mo...

journal_title：Statistics in medicine

authors： Gabriel EE,Sachs MC,Daniels MJ,Halloran ME

更新日期：2019-03-30 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：:The asymptotic Pearson's chi-squared test and Fisher's exact test have long been the most used for testing association in 2x2 tables. Unconditional tests preserve the significance level and generally are more powerful than Fisher's exact test for moderate to small samples, but previously were disadvantaged by being co...

journal_title：Statistics in medicine

authors： Lydersen S,Fagerland MW,Laake P

更新日期：2009-03-30 00:00:00

abstract：:Disease incidence or disease mortality rates for small areas are often displayed on maps. Maps of raw rates, disease counts divided by the total population at risk, have been criticized as unreliable due to non-constant variance associated with heterogeneity in base population size. This has led to the use of model-ba...

journal_title：Statistics in medicine

authors： Stern HS,Cressie N

更新日期：2000-09-15 00:00:00

abstract：:Differences between arm-based (AB) and contrast-based (CB) models for network meta-analysis (NMA) are controversial. We compare the CB model of Lu and Ades (2006), the AB model of Hong et al(2016), and two intermediate models, using hypothetical data and a selected real data set. Differences between models arise prima...

journal_title：Statistics in medicine

authors： White IR,Turner RM,Karahalios A,Salanti G

更新日期：2019-11-30 00:00:00

abstract：:In the last decade or so, pharmaceutical drug development activities in the area of new antibacterial drugs for treating serious bacterial diseases have declined, and at the same time, there are worries that the increased prevalence of antibiotic-resistant bacterial infections, especially the increase in drug-resistan...

journal_title：Statistics in medicine

authors： Huque MF,Valappil T,Soon GG

更新日期：2014-11-10 00:00:00

abstract：:In many studies, a K degree of freedom large sample chi2 test is used to assess the effect of treatment on a multivariate response, such as an omnibus T2-like test of a difference between two treatment groups in any of K repeated measures. Alternately, a K df chi2 test may be used to test the equality of K+1 groups in...

journal_title：Statistics in medicine

authors： Lachin JM,Greenhouse SW,Bautista OM

更新日期：2003-11-15 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 review two recent trends: the emergence of evidence-based medicine and the growing use of Bayesian statistics in medical applications. Evidence-based medicine requires an integrated assessment of the available evidence, and associated uncertainty, but there is also an emphasis on decision-making, for individual pat...

journal_title：Statistics in medicine

authors： Ashby D,Smith AF

更新日期：2000-12-15 00:00:00

abstract：:We consider bivariate survival times for heterogeneous populations, where heterogeneity induces deviations in an individual's risk of an event as well as associations between survival times. The heterogeneity is characterized by a bivariate frailty model. We measure the heterogeneity effects through deviations associa...

journal_title：Statistics in medicine

authors： Xue X,Ding Y

更新日期：1999-04-30 00:00:00

abstract：:We present a method to determine the number of subjects, k, and number of repeated measurements, n, that minimize the overall cost of conducting a reliability study, while providing acceptable power for tests of hypotheses concerning the reliability coefficient rho. Tables showing optimal choices of k and n under vari...

journal_title：Statistics in medicine

authors： Eliasziw M,Donner A

更新日期：1987-09-01 00:00:00

abstract：:We consider counting process methods for analysing time-to-event data with multiple or recurrent outcomes, using the models developed by Anderson and Gill, Wei, Lin and Weissfeld and Prentice, Williams and Peterson. We compare the methods, and show how to implement them using popular statistical software programs. By ...

journal_title：Statistics in medicine

authors： Therneau TM,Hamilton SA

更新日期：1997-09-30 00:00:00

abstract：:This paper discusses and compares several estimators of mean rate of change in unbalanced longitudinal data based on a model with randomly distributed regression coefficients across individuals. The estimators are unweighted and weighted means of these coefficients. The paper also evaluates commonly used variance esti...

journal_title：Statistics in medicine

authors： Palta M,Cook T

更新日期：1987-07-01 00:00:00