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 computed from linear combinations of the observed data. The statistical evaluation of the composite scores is univariate. For studies with a small number of experimental units and with many repeated measures, OPS may offer advantages over the use of summary measures such as the maximum response (MAX), the time at which MAX occurred (TMAX), or the area under the response curve (AUC), and other popular approaches such as time-point-by-time-point, split-plot, and multivariate analyses.
journal_name
Stat Medjournal_title
Statistics in medicineauthors
Bradstreet TEdoi
10.1002/sim.4780120703subject
Has Abstractpub_date
1993-04-15 00:00:00pages
633-43issue
7eissn
0277-6715issn
1097-0258journal_volume
12pub_type
杂志文章abstract::In a long-running longitudinal study using complex machinery to obtain measurements, it is sometimes necessary to replace the machine. This can result in lack of continuity in the measurements that can overwhelm any treatment effect or time trend. We propose a Bayesian procedure implemented using Markov chain Monte Ca...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.1868
更新日期:2004-09-30 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
pub_type: 杂志文章
doi:10.1002/sim.4780100812
更新日期:1991-08-01 00:00:00
abstract::We discuss some of the fundamental concepts underlying the development of frailty and random effects models in survival. One of these fundamental concepts was the idea of a frailty model where each subject has his or her own disposition to failure, their so-called frailty, additional to any effects we wish to quantify...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.1259
更新日期:2002-11-15 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
pub_type: 杂志文章
doi:10.1002/sim.7636
更新日期:2018-05-30 00:00:00
abstract::The log-rank test is the most powerful non-parametric test for detecting a proportional hazards alternative and thus is the most commonly used testing procedure for comparing time-to-event distributions between different treatments in clinical trials. When the log-rank test is used for the primary data analysis, the s...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.3501
更新日期:2009-02-28 00:00:00
abstract::We present an approach for inference on contrasts of clinically meaningful functionals of a survivor distribution (e.g., restricted mean, quantiles) that can avoid strong parametric or semiparametric assumptions on the underlying structure of the data. In this multistage approach, we first use an adaptive predictive m...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.4505
更新日期:2012-07-20 00:00:00
abstract::Patient compliance (adherence) with prescribed medication is often erratic, while clinical outcomes are causally linked to actual, rather than nominal medication dosage. We propose here a hierarchical Markov model for patient compliance. At the first stage, conditional upon individual random effects and a set of indiv...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/(sici)1097-0258(19981030)17:20<2313::aid-s
更新日期:1998-10-30 00:00:00
abstract::The incremental life expectancy, defined as the difference in mean survival times between two treatment groups, is a crucial quantity of interest in cost-effectiveness analyses. Usually, this quantity is very difficult to estimate from censored survival data with a limited follow-up period. The paper develops estimati...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.6951
更新日期:2016-09-10 00:00:00
abstract::Generalized relative and absolute risk models, in which various functions of time and age modify the excess relative or absolute risk of radiation-induced cancer, are fitted to the Japanese atomic bomb survivor cancer incidence data set. Among generalized relative risk models, those in which a product of powers of tim...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/(sici)1097-0258(19990115)18:1<17::aid-sim9
更新日期:1999-01-15 00:00:00
abstract::Risk prediction procedures can be quite useful for the patient's treatment selection, prevention strategy, or disease management in evidence-based medicine. Often, potentially important new predictors are available in addition to the conventional markers. The question is how to quantify the improvement from the new ma...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.5647
更新日期:2013-06-30 00:00:00
abstract::We present a method to estimate the time-dependent vaccine efficacy from the cohort-specific vaccination coverage and from data on the vaccination status of cases and apply it to a measles epidemic in Germany which involved 529 cases, 88 of whom were vaccinated and 370 unvaccinated (for the remaining 71 cases the vacc...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.1043
更新日期:2002-08-30 00:00:00
abstract::Multivariate random length data occur when we observe multiple measurements of a quantitative variable and the variable number of these measurements is also an observed outcome for each experimental unit. For example, for a patient with coronary artery disease, we may observe a number of lesions in that patient's coro...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/(sici)1097-0258(19990130)18:2<199::aid-sim
更新日期:1999-01-30 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
pub_type: 杂志文章
doi:10.1002/sim.1506
更新日期:2003-05-15 00:00:00
abstract::We investigate a binary partitioning algorithm in the case of a continuous repeated measures outcome. The procedure is based on the use of the likelihood ratio statistic to evaluate the performance of individual splits. The procedure partitions a set of longitudinal data into two mutually exclusive groups based on an ...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.1266
更新日期:2002-11-30 00:00:00
abstract::Random forest is a supervised learning method that combines many classification or regression trees for prediction. Here we describe an extension of the random forest method for building event risk prediction models in survival analysis with competing risks. In case of right-censored data, the event status at the pred...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.5775
更新日期:2013-08-15 00:00:00
abstract::In many medical applications, combining information from multiple biomarkers could yield a better diagnosis than any single one on its own. When there is a lack of a gold standard, an algorithm of classifying subjects into the case and non-case status is necessary for combining multiple markers. The aim of this paper ...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.6780
更新日期:2016-04-15 00:00:00
abstract::In this paper we examine the efficiency of a generalization of the traditional normal linear (LDA) or quadratic (QDA) discriminant analysis. This procedure (the generalized discriminant analysis, GDA) replaces each normal density used in the traditional classification rule by a Fourier series density estimator which '...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.4780100319
更新日期:1991-03-01 00:00:00
abstract::Assessment of quality of life is becoming standard in clinical trials. A popular method for measuring quality of life is with instruments which utilize multiple-item subscales, in which each item is scored on a Likert scale. Most statistical methods for the analysis of quality of life data in clinical trials do not ex...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/(sici)1097-0258(19991115)18:21<2917::aid-s
更新日期:1999-11-15 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
pub_type: 杂志文章
doi:10.1002/sim.3561
更新日期:2009-05-01 00:00:00
abstract::Meta-analysis is the methodology for combining findings from similar research studies asking the same question. When the question of interest involves multiple outcomes, multivariate meta-analysis is used to synthesize the outcomes simultaneously taking into account the correlation between the outcomes. Likelihood-bas...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.4327
更新日期:2011-10-30 00:00:00
abstract::The design of a cross-sectional survey to estimate the age-specific incidence of an irreversible disease is considered, where the incidence rate is not changing over time and the risk of mortality is not affected by the onset of disease. The sample is assumed to give information on the current age and disease status o...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.4780132208
更新日期:1994-11-30 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
pub_type: 杂志文章
doi:10.1002/sim.4780080110
更新日期:1989-01-01 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
pub_type: 杂志文章
doi:10.1002/sim.2524
更新日期:2007-01-15 00:00:00
abstract::With reference to a real data on cataract surgery, we discuss the problem of zero-inflated circular-circular regression when both covariate and response are circular random variables and a large proportion of the responses are zeros. The regression model is proposed, and the estimation procedure for the parameters is ...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.7496
更新日期:2018-01-15 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
pub_type: 杂志文章
doi:10.1002/sim.3830
更新日期:2010-03-15 00:00:00
abstract::Among subjects who have experienced a biological event, such as menarche, menopause or a delivery, one cannot distinguish the effects of time since the event from age at the event due to the linear dependency among these time variables and age at study ('current age'). This is a well-known problem that also exists in ...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/(SICI)1097-0258(19960730)15:14<1545::AID-S
更新日期:1996-07-30 00:00:00
abstract::The power to detect a treatment effect in cluster randomized trials can be increased by increasing the number of clusters. An alternative is to include covariates into the regression model that relates treatment condition to outcome. In this paper, formulae are derived in order to evaluate both strategies on basis of ...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.2297
更新日期:2006-08-15 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
pub_type: 杂志文章
doi:10.1002/sim.4780131809
更新日期:1994-09-30 00:00:00
abstract::In a recent Statistics in Medicine paper, Warn, Thompson and Spiegelhalter (WTS) made a comparison between the Bayesian approach to the meta-analysis of binary outcomes and a popular Classical approach that uses summary (two-stage) techniques. They included approximate summary (two-stage) Bayesian techniques in their ...
journal_title:Statistics in medicine
pub_type: 评论,信件
doi:10.1002/sim.2115
更新日期:2005-09-15 00:00:00
abstract::We discuss the use of the trichotomous logistic model to discriminate between patients with gastrointestinal (GI) cancer, patients with benign GI disease and 'normal' subjects, using symptoms and the concentrations of some serum proteins that are potentially indicative of malignancy as covariates. A parsimonious model...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.4780040313
更新日期:1985-07-01 00:00:00