Power and sample size determination for group comparison of patient-reported outcomes using polytomous Rasch models.

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：: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：:The Wilcoxon-Mann-Whitney (WMW) test is often used to compare the means or medians of two independent, possibly nonnormal distributions. For this problem, the true significance level of the large sample approximate version of the WMW test is known to be sensitive to differences in the shapes of the distributions. Base...

journal_title：Statistics in medicine

authors： Fagerland MW,Sandvik L

更新日期：2009-05-01 00:00:00

abstract：:Binary matched-pairs data occur commonly in longitudinal studies, such as in cross-over experiments. Many analyses for comparing the matched probabilities of a particular outcome do not utilize pairs having the same outcome for each observation. An example is McNemar's test. Some methodologists find this to be counter...

journal_title：Statistics in medicine

authors： Agresti A,Min Y

更新日期：2004-01-15 00:00:00

abstract：:In lifetime data, like cancer studies, there may be long term survivors, which lead to heavy censoring at the end of the follow-up period. Since a standard survival model is not appropriate to handle these data, a cure model is needed. In the literature, covariate hypothesis tests for cure models are limited to parame...

journal_title：Statistics in medicine

authors： López-Cheda A,Jácome MA,Van Keilegom I,Cao R

更新日期：2020-07-30 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：:Assay sensitivity has been proposed as a criterion for including psychiatric clinical outcome studies in meta-analyses. The authors assess the performance of assay sensitivity as a method for determining study appropriateness for meta-analysis by calculating expected standard drug vs placebo effect sizes for various c...

journal_title：Statistics in medicine

authors： Gelfand LA,Strunk DR,Tu XM,Noble RE,Derubeis RJ

更新日期：2006-03-30 00:00:00

abstract：:Multi-state models are useful for modelling disease progression where the state space of the process is used to represent the discrete disease status of subjects. Often, the disease process is only observed at clinical visits, and the schedule of these visits can depend on the disease status of patients. In such situa...

journal_title：Statistics in medicine

authors： Lesperance ML,Sabelnykova V,Nathoo FS,Lau F,Downing MG

更新日期：2015-12-20 00:00:00

abstract：:Orthogonal polynomial scores (OPS) is a simple, biologically meaningful approach to characterize longitudinal data in phase I and II clinical pharmacology trials. It describes average, linear, quadratic and higher order polynomial characteristics of each subject's response over time with use of composite scores comput...

journal_title：Statistics in medicine

authors： Bradstreet TE

更新日期：1993-04-15 00:00:00

abstract：:In population-based case-control studies, an attempt is made to identify all incident cases diagnosed in a specified population during a fixed time interval. Assuming that this goal is met allows one to obtain measures of risk other than relative risks. In this paper, we describe three approaches to estimate exposure-...

journal_title：Statistics in medicine

authors： Benichou J,Wacholder S

更新日期：1994-03-15 00:00:00

abstract：:We propose the use of Gaussian mixed models to analyse statistically 24 hour ambulatory blood pressure data from clinical trials. We develop specific models and apply them to data from a clinical study that compares two angiotensin-converting enzyme inhibitors. We investigate and discuss computing issues related to th...

journal_title：Statistics in medicine

authors： Selwyn MR,Difranco DM

更新日期：1993-09-30 00:00:00

abstract：:We present a new method of detection and inference for spatial clusters of a disease. To avoid ad hoc procedures to test for clustering, we have a clearly defined alternative hypothesis and our test statistic is based on the likelihood ratio. The proposed test can detect clusters of any size, located anywhere in the s...

journal_title：Statistics in medicine

authors： Kulldorff M,Nagarwalla N

更新日期：1995-04-30 00:00:00

abstract：:In this paper we give an informal introduction to a robust method for survival analysis which is based on a modification of the usual partial likelihood estimator (PLE). Large sample results lead us to expect reduced bias for this robust estimator compared with the PLE whenever there are even slight violations of the ...

journal_title：Statistics in medicine

authors： Minder CE,Bednarski T

更新日期：1996-05-30 00:00:00

abstract：:Unmeasured confounding is a common concern when researchers attempt to estimate a treatment effect using observational data or randomized studies with nonperfect compliance. To address this concern, instrumental variable methods, such as 2-stage predictor substitution (2SPS) and 2-stage residual inclusion (2SRI), have...

journal_title：Statistics in medicine

authors： Wan F,Small D,Mitra N

更新日期：2018-05-30 00:00:00

abstract：:We develop analysis methods for clinical trials with time-to-event outcomes which correct for treatment changes during follow-up, yet are based on comparisons of randomized groups and not of selected groups. A causal model relating observed event times to event times that would have been observed under other treatment...

journal_title：Statistics in medicine

authors： White IR,Babiker AG,Walker S,Darbyshire JH

更新日期：1999-10-15 00:00:00

abstract：:This paper presents a statistically optimal exact hypothesis testing procedure for detecting changes in sales adjusted adverse drug reaction (ADR) rates between historical and current periods, with a computer program that implements this test appended. We provide discussions and illustrations on how to monitor ADR rat...

journal_title：Statistics in medicine

authors： Norwood PK,Sampson AR

更新日期：1988-10-01 00:00:00

abstract：:In case-control studies, the Cochran-Armitage (CA) trend test is powerful for detection of an association between a risk allele and a marker. To apply this test, a score should be assigned to the genotypes based on the genetic model. When the underlying genetic model is unknown, the trend test statistic is a function ...

journal_title：Statistics in medicine

authors： Zheng G

更新日期：2003-08-30 00:00:00

abstract：:We describe rank-based approaches to assess principal stratification treatment effects in studies where the outcome of interest is only well-defined in a subgroup selected after randomization. Our methods are sensitivity analyses, in that estimands are identified by fixing a parameter and then we investigate the sensi...

journal_title：Statistics in medicine

authors： Lu X,Mehrotra DV,Shepherd BE

更新日期：2013-11-20 00:00:00

abstract：:In this paper, we discuss family-based association test (FBATs) relating genetic data to survival and time-to-onset data. We show how the standard logrank and Wilcoxon statistics can be used with family data to develop tests of association. We prove that the FBAT-logrank approach can be identical to the proportional h...

journal_title：Statistics in medicine

authors： Lange C,Blacker D,Laird NM

更新日期：2004-01-30 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：:We have formulated the problem of determining whether there has been an upturn in HIV-1 seroconversion incidence over the first five years of follow-up in the Multicenter AIDS Cohort Study (MACS) as that of locating the minimum of a quadratic regression or examination of two-knot piecewise spline models. Under a quadr...

journal_title：Statistics in medicine

authors： Zhou SY,Kingsley LA,Taylor JM,Chmiel JS,He DY,Hoover DR

更新日期：1993-01-30 00:00:00

abstract：:Motivated by a previously published study of HIV treatment, we simulated data subject to time-varying confounding affected by prior treatment to examine some finite-sample properties of marginal structural Cox proportional hazards models. We compared (a) unadjusted, (b) regression-adjusted, (c) unstabilized, and (d) s...

journal_title：Statistics in medicine

authors： Westreich D,Cole SR,Schisterman EF,Platt RW

更新日期：2012-08-30 00:00:00

abstract：:Analyses to compare non-randomized groups are more and more common in both post hoc analyses of randomized clinical trials data and in analyses of long-term observational data. In such cases, it is quite likely that there are unknown or uncollected sources of heterogeneity in event rates. Research has shown that an un...

journal_title：Statistics in medicine

authors： Eberly LE

更新日期：2004-07-15 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：: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：:Kappa coefficients are measures of correlation between categorical variables often used as reliability or validity coefficients. We recapitulate development and definitions of the K (categories) by M (ratings) kappas (K x M), discuss what they are well- or ill-designed to do, and summarize where kappas now stand with ...

journal_title：Statistics in medicine

authors： Chmura Kraemer H,Periyakoil VS,Noda A

更新日期：2002-07-30 00:00:00

abstract：:Although statistical methodology is well-developed for comparing diagnostic tests in terms of their sensitivity and specificity, comparative inference about predictive values is not. In this paper, we consider the analysis of studies comparing operating characteristics of two diagnostic tests that are measured on all ...

journal_title：Statistics in medicine

authors： Kwak M,Um SW,Jung SH

更新日期：2015-07-10 00:00:00

abstract：:In designed longitudinal studies, information from the same set of subjects are collected repeatedly over time. The longitudinal measurements are often subject to missing data which impose an analytic challenge. We propose a functional multiple imputation approach modeling longitudinal response profiles as smooth curv...

journal_title：Statistics in medicine

authors： He Y,Yucel R,Raghunathan TE

更新日期：2011-05-10 00:00:00

abstract：:This article deals with determination of a sample size that guarantees the success of a trial. We follow a Bayesian approach and we say an experiment is successful if it yields a large posterior probability that an unknown parameter of interest (an unknown treatment effect or an effects-difference) is greater than a c...

journal_title：Statistics in medicine

authors： Brutti P,De Santis F,Gubbiotti S

更新日期：2008-06-15 00:00:00

abstract：:A popular method to control multiplicity in confirmatory clinical trials is to use a so-called hierarchical, or fixed sequence, test procedure. This requires that the null hypotheses are ordered a priori, for example, in order of clinical importance. The procedure tests the hypotheses in this order using alpha-level t...

journal_title：Statistics in medicine

authors： Edwards D,Madsen J

更新日期：2007-12-10 00:00:00