Abstract:
:The Cardiac Arrythmia Suppression Trial was stopped much earlier than planned. Statistical considerations played a very important role in the decision. Flexible group sequential testing was developed for the trial by implementing a Lan and DeMets procedure with use of the permutation test. We compute P-values from the joint permutation distribution of the test statistics, so we do not need to estimate the sampling distribution which in general is rather difficult to do without strict assumptions. The method also gives an exact test for small samples and allows us to use more complicated or non-Gaussian statistics. We also utilized stochastic curtailment ideas to evaluate various scenarios that might occur during the course of the trial, which assisted the Data and Safety Monitoring Board in making appropriate decisions.
journal_name
Stat Medjournal_title
Statistics in medicineauthors
Pawitan Y,Hallstrom Adoi
10.1002/sim.4780090915subject
Has Abstractpub_date
1990-09-01 00:00:00pages
1081-90issue
9eissn
0277-6715issn
1097-0258journal_volume
9pub_type
临床试验,杂志文章,多中心研究,随机对照试验abstract::A new, intuitive method has recently been proposed to explore treatment-covariate interactions in survival data arising from two treatment arms of a clinical trial. The method is based on constructing overlapping subpopulations of patients with respect to one (or more) covariates of interest and in observing the patte...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.3524
更新日期:2009-04-15 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
pub_type: 杂志文章
doi:10.1002/sim.3303
更新日期:2008-07-30 00:00:00
abstract::In this paper, we define a modified version τ(b) of Kendall's tau to measure the association in a pair (X,Y) of random variables subject to fixed left censoring due to known lower detection limits. We provide a nonparametric estimator of τ(b) and investigate its asymptotic properties. We then assume an Archimedean cop...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.4319
更新日期:2011-11-20 00:00:00
abstract::In clinical research, investigators are interested in inferring the average causal effect of a treatment. However, the causal parameter that can be used to derive the average causal effect is not well defined for ordinal outcomes. Although some definitions have been proposed, they are limited in that they are not iden...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.7400
更新日期:2017-11-10 00:00:00
abstract::In medical research, risk difference (RD) and number needed to treat (NNT) measures for survival times have been mainly proposed without consideration of covariates. In this paper, we develop adjusted RD and NNT measures for use in observational studies with survival time outcomes within the framework of the Cox propo...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.3793
更新日期:2010-03-30 00:00:00
abstract::A relationship between baseline risk and treatment effect is increasingly investigated as a possible explanation of between-study heterogeneity in clinical trial meta-analysis. An approach that is still often applied in the medical literature is to plot the estimated treatment effects against the estimated measures of...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/1097-0258(20001230)19:24<3497::aid-sim830>
更新日期:2000-12-30 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::We provide a Bayesian analysis of data categorized into two levels of age (younger than 50 years, at least 50 years) and three levels of bone mineral density (normal, osteopenia, osteoporosis) for white females at least 20 years old in the third National Health and Nutrition Examination Survey. For the sample, the age...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.1985
更新日期:2005-04-15 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::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
pub_type: 评论,杂志文章
doi:10.1002/sim.923
更新日期:2001-10-30 00:00:00
abstract::The additional time to complete a three-period two-treatment (3P2T) cross-over trial may cause a greater number of patient dropouts than with a two-period trial. This paper develops maximum likelihood (ML), single imputation and multiple imputation missing data analysis methods for the 3P2T cross-over designs. We use ...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/(SICI)1097-0258(19960130)15:2<127::AID-SIM
更新日期:1996-01-30 00:00:00
abstract::The first randomized clinical trial at the National Cancer Institute (NCI), planned in 1954, commenced in 1955 for the treatment of patients with acute leukaemia. The programme in clinical trials at NCI had strong influence from the clinician and administrator, C. Gordon Zubrod, who introduced the randomized clinical ...
journal_title:Statistics in medicine
pub_type: 临床试验,历史文章,杂志文章,随机对照试验
doi:10.1002/sim.4780090803
更新日期:1990-08-01 00:00:00
abstract::The analysis and recognition of disease clustering in space and its representation on a map is an important problem in epidemiology. An approach using mixture models to identify spatial heterogeneity in disease risk and map construction within an empirical Bayes framework is described. Once heterogeneity is detected, ...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/(sici)1097-0258(19960415)15:7/9<919::aid-s
更新日期:1996-04-15 00:00:00
abstract::Detecting safety signals in clinical trial safety data is known to be challenging due to high dimensionality, rare occurrence, weak signal, and complex dependence. We propose a new hierarchical testing approach for analyzing safety data from a typical randomized clinical trial. This approach accounts for the hierarchi...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.8495
更新日期:2020-05-15 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
pub_type: 杂志文章
doi:10.1002/(sici)1097-0258(19990815)18:15<1973::aid-s
更新日期:1999-08-15 00:00:00
abstract::Shared random effects models have been increasingly common in the joint analyses of repeated measures (e.g. CD4 counts, hemoglobin levels) and a correlated failure time such as death. In this paper we study several shared random effects models in the multi-level repeated measures data setting with dependent failure ti...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.3392
更新日期:2008-11-29 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
pub_type: 杂志文章
doi:10.1002/sim.4780100512
更新日期:1991-05-01 00:00:00
abstract::The two tailed Fisher's exact P value is extremely sensitive to small perturbations in 2 x 2 contingency tables. An example indicates that a 1 per cent increase in the denominator of one treatment group results in a 32 per cent drop in the exact P value, but a mere 0.1 per cent decrease in the treatment success rate. ...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.4780050610
更新日期:1986-11-01 00:00:00
abstract::For massive survival data, we propose a subsampling algorithm to efficiently approximate the estimates of regression parameters in the additive hazards model. We establish consistency and asymptotic normality of the subsample-based estimator given the full data. The optimal subsampling probabilities are obtained via m...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.8783
更新日期:2021-01-30 00:00:00
abstract::Group sequential hypothesis testing is now widely used to analyze prospective data. If Monte Carlo simulation is used to construct the signaling threshold, the challenge is how to manage the type I error probability for each one of the multiple tests without losing control on the overall significance level. This paper...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.6805
更新日期:2016-04-30 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
pub_type: 杂志文章,多中心研究
doi:10.1002/sim.4780120207
更新日期:1993-01-30 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::Interval-censored survival data often occur in medical studies, especially in clinical trials. In this case, many authors have considered estimation of a survival function. There is, however, relatively little discussion on estimating the variance of estimated survival functions. For right-censored data, a special cas...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.719
更新日期:2001-04-30 00:00:00
abstract::We propose to use a very simple model to test whether a cancer cluster is due to chance alone. We focus on the acute childhood leukaemia cluster in Columbus, Ohio. In 1975, 12 leukaemia cases were observed in Columbus while the expected number is 6 cases per year. According to our simple model, the probability of such...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/1097-0258(20000830)19:16<2195::aid-sim522>
更新日期:2000-08-30 00:00:00
abstract::Prediction performance of a risk scoring system needs to be carefully assessed before its adoption in clinical practice. Clinical preventive care often uses risk scores to screen asymptomatic population. The primary clinical interest is to predict the risk of having an event by a prespecified future time t0 . Accuracy...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.7606
更新日期:2018-05-10 00:00:00
abstract::Instrumental variable is an essential tool for addressing unmeasured confounding in observational studies. Two-stage predictor substitution (2SPS) estimator and two-stage residual inclusion (2SRI) are two commonly used approaches in applying instrumental variables. Recently, 2SPS was studied under the additive hazards...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.8071
更新日期:2019-05-10 00:00:00
abstract::When estimating the average effect of a binary treatment (or exposure) on an outcome, methods that incorporate propensity scores, the G-formula, or targeted maximum likelihood estimation (TMLE) are preferred over naïve regression approaches, which are biased under misspecification of a parametric outcome model. In con...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.7628
更新日期:2018-07-20 00:00:00
abstract::Assessing the calibration of methods for estimating the probability of the occurrence of a binary outcome is an important aspect of validating the performance of risk-prediction algorithms. Calibration commonly refers to the agreement between predicted and observed probabilities of the outcome. Graphical methods are a...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.8281
更新日期:2019-09-20 00:00:00
abstract::R2 has been criticized as a measure of model performance when predicting a dichotomous outcome, both because its value is often low and because it is sensitive to the prevalence of the event of interest. The C statistic is more widely used to measure model performance in a 0/1 setting. We use a simple parametric famil...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/(sici)1097-0258(19990228)18:4<375::aid-sim
更新日期:1999-02-28 00:00:00
abstract::The explanation of heterogeneity plays an important role in meta-analysis. The random effects meta-regression model allows the inclusion of trial-specific covariates which may explain a part of the heterogeneity. We examine the commonly used tests on the parameters in the random effects meta-regression with one covari...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.1482
更新日期:2003-09-15 00:00:00