Consequences of event rate heterogeneity across non-randomized study sub-groups.

abstract：:Weak measurement of epidemiologic exposures is an impediment to appreciation of the effects of those exposures. This paper discusses two strategies to assess the true effects of weakly measured exposure. The first is to use external information about the extent of mismeasurement to adjust estimates of the effects of e...

journal_title：Statistics in medicine

authors： Marshall JR

更新日期：1989-09-01 00:00:00

abstract：:The use of outcome-dependent sampling with longitudinal data analysis has previously been shown to improve efficiency in the estimation of regression parameters. The motivating scenario is when outcome data exist for all cohort members but key exposure variables will be gathered only on a subset. Inference with outcom...

journal_title：Statistics in medicine

authors： Zelnick LR,Schildcrout JS,Heagerty PJ

更新日期：2018-06-15 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：:Nutritional exposures are often measured with considerable error in commonly used surrogate instruments such as the food frequency questionnaire (FFQ) (denoted by Q(i) for the ith subject). The error can be both systematic and random. The diet record (DR) denoted by R(i) for the ith subject is considered an alloyed go...

journal_title：Statistics in medicine

authors： Rosner B,Michels KB,Chen YH,Day NE

更新日期：2008-08-15 00:00:00

abstract：:Slow recruitment in clinical trials leads to increased costs and resource utilization, which includes both the clinic staff and patient volunteers. Careful planning and monitoring of the accrual process can prevent the unnecessary loss of these resources. We propose two hierarchical extensions to the existing Bayesian...

journal_title：Statistics in medicine

authors： Jiang Y,Simon S,Mayo MS,Gajewski BJ

更新日期：2015-02-20 00:00:00

abstract：:Combining multiple markers can improve classification accuracy compared with using a single marker. In practice, covariates associated with markers or disease outcome can affect the performance of a biomarker or biomarker combination in the population. The covariate-adjusted receiver operating characteristic (ROC) cur...

journal_title：Statistics in medicine

authors： Kim S,Huang Y

更新日期：2017-07-10 00:00:00

abstract：:Matched-pair designs have been commonly employed in diagnostic, epidemiologic and laboratory studies. For estimation of a ratio of two marginal probabilities in matched-pair data, a Wald-type logarithmic method is computationally simple, but an actual coverage rate is known to be smaller than a nominal one and a lengt...

journal_title：Statistics in medicine

authors： Nam JM

更新日期：2009-10-15 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：:Statistical tests have been proposed for determining whether incident cases of adverse health effects are 'clustered' together. Several procedures, termed 'focused', specifically analyse disease surveillance data around pre-specified putative sources of environmental hazard. Little has been done to compare the perform...

journal_title：Statistics in medicine

authors： Waller LA,Lawson AB

更新日期：1995-11-15 00:00:00

abstract：:We consider several sources of heterogeneity in a clinical trial with patients' survival time as the main response criterion: differences in prognosis which can be attributed to a latent or ignored prognostic factor; differences in treatment efficacy in subgroups of patients, and differences in treatment combinations ...

journal_title：Statistics in medicine

authors： Schumacher M,Olschewski M,Schmoor C

更新日期：1987-10-01 00:00:00

abstract：:In analysis of longitudinal data, the variance matrix of the parameter estimates is usually estimated by the 'sandwich' method, in which the variance for each subject is estimated by its residual products. We propose smooth bootstrap methods by perturbing the estimating functions to obtain 'bootstrapped' realizations ...

journal_title：Statistics in medicine

authors： Li Y,Wang YG

更新日期：2008-03-30 00:00:00

abstract：:The Spearman (rho(s)) and Kendall (tau) rank correlation coefficient are routinely used as measures of association between non-normally distributed random variables. However, confidence limits for rho(s) are only available under the assumption of bivariate normality and for tau under the assumption of asymptotic norma...

journal_title：Statistics in medicine

authors： Rosner B,Glynn RJ

更新日期：2007-02-10 00:00:00

abstract：:Biostatisticians have frequently uncritically accepted the measurements provided by their medical colleagues engaged in clinical research. Such measures often involve considerable loss of information. Particularly, unfortunate is the widespread use of the so-called 'responder analysis', which may involve not only a lo...

journal_title：Statistics in medicine

authors： Senn S,Julious S

更新日期：2009-11-20 00:00:00

abstract：:While there has been extensive research developing gene-environment interaction (GEI) methods in case-control studies, little attention has been given to sparse and efficient modeling of GEI in longitudinal studies. In a two-way table for GEI with rows and columns as categorical variables, a conventional saturated int...

journal_title：Statistics in medicine

authors： Ko YA,Mukherjee B,Smith JA,Park SK,Kardia SL,Allison MA,Vokonas PS,Chen J,Diez-Roux AV

更新日期：2014-12-20 00:00:00

abstract：:Selection of dose for cancer patients treated with radiation therapy (RT) must balance the increased efficacy with the increased toxicity associated with higher dose. Historically, a single dose has been selected for a population of patients (e.g., all stage III non-small cell lung cancer). However, the availability o...

journal_title：Statistics in medicine

authors： Schipper MJ,Taylor JM,TenHaken R,Matuzak MM,Kong FM,Lawrence TS

更新日期：2014-12-30 00:00:00

abstract：:In this work, we describe a two-stage sampling design to estimate the infection prevalence in a population. In the first stage, an imperfect diagnostic test was performed on a random sample of the population. In the second stage, a different imperfect test was performed in a stratified random sample of the first sampl...

journal_title：Statistics in medicine

authors： Miller E,Huppert A,Novikov I,Warburg A,Hailu A,Abbasi I,Freedman LS

更新日期：2015-11-10 00:00:00

abstract：:Outcome-dependent sampling (ODS) scheme is a cost-effective sampling scheme where one observes the exposure with a probability that depends on the outcome. The well-known such design is the case-control design for binary response, the case-cohort design for the failure time data, and the general ODS design for a conti...

journal_title：Statistics in medicine

authors： Lu TS,Longnecker MP,Zhou H

更新日期：2017-03-15 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：:When estimating the probability of natural conception from observational data on couples with an unfulfilled child wish, the start of assisted reproductive therapy (ART) is a competing event that cannot be assumed to be independent of natural conception. In clinical practice, interest lies in the probability of natura...

journal_title：Statistics in medicine

authors： van Geloven N,Geskus RB,Mol BW,Zwinderman AH

更新日期：2014-11-20 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：:Mesothelioma is a rare cancer caused by exposure to asbestos. Belgium has a known long history of asbestos production, resulting in one of the highest mesothelioma mortality rates worldwide. While the production of asbestos has stopped completely, the long latency period of mesothelioma, which can fluctuate between 20...

journal_title：Statistics in medicine

authors： Petrof O,Neyens T,Nuyts V,Nackaerts K,Nemery B,Faes C

更新日期：2020-11-20 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 purpose of this paper is to show that the sensitivity and specificity estimates obtained by 'discrepant analysis' are biased. Discrepant analysis is a widely used technique that attempts to provide estimates of sensitivity and specificity in the presence of an imperfect gold standard. Many researchers have applied...

journal_title：Statistics in medicine

authors： Hadgu A

更新日期：1997-06-30 00:00:00

abstract：:Within the rich literature on generalized linear models, substantial efforts have been devoted to models for categorical responses that are either completely ordered or completely unordered. Few studies have focused on the analysis of partially ordered outcomes, which arise in practically every area of study, includin...

journal_title：Statistics in medicine

authors： Zhang Q,Ip EH

更新日期：2012-01-13 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：:Clinical research often involves continuous outcome measures, such as blood cholesterol, that are amenable to statistical techniques of analysis based on the mean, such as the t-test or multiple linear regression. Clinical interest, however, frequently focuses on the proportion of subjects who fall below or above a cl...

journal_title：Statistics in medicine

authors： Suissa S,Blais L

更新日期：1995-02-15 00:00:00

abstract：:Correlated response data arise often in biomedical studies. The generalized estimation equation (GEE) approach is widely used in regression analysis for such data. However, there are few methods available to check the adequacy of regression models in GEE. In this paper, a graphical method is proposed based on Cook and...

journal_title：Statistics in medicine

authors： Pan W,Connett JE,Porzio GC,Weisberg S

更新日期：2001-10-15 00:00:00

abstract：:This paper introduces a new spatial scan statistic designed to adjust cluster detection for longitudinal confounding factors indexed in space. The functional-model-adjusted statistic was developed using generalized functional linear models in which longitudinal confounding factors were considered to be functional cova...

journal_title：Statistics in medicine

authors： Ahmed MS,Genin M

更新日期：2020-04-15 00:00:00

abstract：:It is often assumed that randomisation will prevent bias in estimation of treatment effects from clinical trials, but this is not true of the semiparametric Proportional Hazards model for survival data when there is underlying risk heterogeneity. Here, a new formula is proposed for estimation of this bias, improving o...

journal_title：Statistics in medicine

authors： McNamee R

更新日期：2017-09-20 00:00:00

abstract：:The induced smoothing technique overcomes the difficulties caused by the non-smoothness in rank-based estimating functions for accelerated failure time models, but it is only natural when the estimating function has Gehan's weight. For a general weight, the induced smoothing method does not provide smooth estimating f...

journal_title：Statistics in medicine

authors： Chiou S,Kang S,Yan J

更新日期：2015-04-30 00:00:00