Analysis of antiretroviral immunotherapy trials with potentially non-normal and incomplete longitudinal data.

abstract：:Interval-censored data are commonly found in studies of diseases that progress without symptoms, which require clinical evaluation for detection. Several techniques have been suggested with independent assumption. However, the assumption will not be valid if observations come from clusters. Furthermore, when the clust...

journal_title：Statistics in medicine

authors： Kim YJ

更新日期：2010-12-10 00:00:00

abstract：:Proportional odds regression models for multinomial probabilities based on ordered categories have been generalized in two somewhat different directions. Models having scale as well as location parameters for adjustment of boundaries (on an unobservable, underlying continuum) between categories have been employed in t...

journal_title：Statistics in medicine

authors： Cox C

更新日期：1995-06-15 00:00:00

abstract：:Cox proportional hazard regression model is a popular tool to analyze the relationship between a censored lifetime variable with other relevant factors. The semiparametric Cox model is widely used to study different types of data arising from applied disciplines such as medical science, biology, and reliability studie...

journal_title：Statistics in medicine

authors： Ghosh A,Basu A

更新日期：2019-11-30 00:00:00

abstract：:Flexible survival models are in need when modelling data from long term follow-up studies. In many cases, the assumption of proportionality imposed by a Cox model will not be valid. Instead, a model that can identify time varying effects of fixed covariates can be used. Although there are several approaches that deal ...

journal_title：Statistics in medicine

authors： Perperoglou A

更新日期：2016-12-10 00:00:00

abstract：:We develop reinforcement learning trials for discovering individualized treatment regimens for life-threatening diseases such as cancer. A temporal-difference learning method called Q-learning is utilized that involves learning an optimal policy from a single training set of finite longitudinal patient trajectories. A...

journal_title：Statistics in medicine

authors： Zhao Y,Kosorok MR,Zeng D

更新日期：2009-11-20 00:00:00

abstract：:Exposure to a carcinogen is likely to be reflected by temporal clustering of cancer cases among the community members. Detection of such clustering is a complicated task in general and more so in a small workplace community with low turnover rate. In this study we applied the CUSCORE test and the q-interval statistic ...

journal_title：Statistics in medicine

authors： Chen R,Froom P

更新日期：2003-10-15 00:00:00

abstract：:Two features commonly exhibited by randomized trials of health promotion interventions are cluster randomization and stratification. Ignoring correlations between individuals within clusters can lead to an inflated type I error rate and hence a P-value which overstates the significance of the result. This paper compar...

journal_title：Statistics in medicine

authors： Dobbins TA,Simpson JM

更新日期：2002-12-30 00:00:00

abstract：:This paper presents a simple method for estimation of population vaccination effectiveness, which is the fraction of disease cases prevented by a vaccination programme. The method is based on the susceptible-infectious-recovered (SIR) model for the spread of an epidemic in a heterogeneous population under non-homogene...

journal_title：Statistics in medicine

authors： Haber M

更新日期：1997-03-30 00:00:00

abstract：:Graphical methods based on the analysis of differences between log cumulative hazard functions are considered for a two-group semi-proportional hazard model which allows for interaction between treatments and covariates. Confidence procedures and test statistics that can be used to test for interaction and for main ef...

journal_title：Statistics in medicine

authors： Dabrowska DM,Doksum KA,Feduska NJ,Husing R,Neville P

更新日期：1992-08-01 00:00:00

abstract：:Estimating the causal effect of quitting smoking on time to death or first myocardial infarction requires that one control for the differences in risk factors between individuals who elect to quite at each time t versus those who elect to continue smoking at time t. In this paper we examine the limitations of standard...

journal_title：Statistics in medicine

authors： Mark SD,Robins JM

更新日期：1993-09-15 00:00:00

abstract：:We simulated multinomial AIDS incidence counts from 27 'representative' AIDS epidemics that spanned a period corresponding to previous applications of backcalculation (1 January 1977 to 1 July 1987) and assessed mean square error for several back-calculated estimators of HIV prevalence and short-term AIDS projections....

journal_title：Statistics in medicine

authors： Rosenberg PS,Gail MH,Pee D

更新日期：1991-08-01 00:00:00

abstract：BACKGROUND:Multiple imputation is becoming increasingly popular for handling missing data, with Markov chain Monte Carlo assuming multivariate normality (MVN) a commonly used approach. Imputing categorical variables (which are clearly non-normal) using MVN imputation is challenging, and several approaches have been sug...

journal_title：Statistics in medicine

authors： Lee KJ,Galati JC,Simpson JA,Carlin JB

更新日期：2012-12-30 00:00:00

abstract：:In this commentary, we revisit Sir Austin Bradford Hill's seminal Alfred Watson Memorial Lecture in 1962 through the eyes of two practicing biostatisticians of the current era. We summarize some eternal takeaway messages from Hill's lecture regarding observations and experiments translated through the modern lexicon o...

journal_title：Statistics in medicine

authors： Dempsey W,Mukherjee B

更新日期：2021-01-15 00:00:00

abstract：:The FDA Guidance, while highly appropriate for industry sponsored trials, need not be imposed on publicly (e.g. NIH) financed clinical trials. While the potential for conflicts of interest exist in the latter, they are in general manageable and pose an acceptable low risk of threatening the integrity of a study. Howev...

journal_title：Statistics in medicine

authors： Lachin JM

更新日期：2004-05-30 00:00:00

abstract：:Crossover studies have been successfully conducted in the case of continuous responses. Existing procedures of analysis for ordinal responses, on the other hand, are rarely satisfactory unless strict, usually unrealistic, assumptions are made. In this paper we investigate a random effects model and show that the model...

journal_title：Statistics in medicine

authors： Ezzet F,Whitehead J

更新日期：1991-06-01 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

authors： Molenberghs G,Geys H,Buyse M

更新日期：2001-10-30 00:00:00

abstract：:Estimates of analyte concentrations, obtained by immunoassay, have error distributions which are generally underestimated. Better estimates, which take into account the distribution of the response metameter of the calibration curve and uncertainties associated with the location of the fitted curve, have been obtained...

journal_title：Statistics in medicine

authors： Kay C,Nix AB,Kemp KW,Rowlands RJ,Richards G,Groom GV,Griffiths K,Wilson DW

更新日期：1986-03-01 00:00:00

abstract：:New combination regimens evaluated in phase II cancer clinical trials often show promising results compared to the standard therapy for a disease system. Selection of patients with a better prognosis can be a prominent factor for this optimism. For most disease systems, prognostic variables that are related to the out...

journal_title：Statistics in medicine

authors： Mazumdar M,Fazzari M,Panageas KS

更新日期：2001-03-30 00:00:00

abstract：:Elevated plasma levels of apolipoproteins A1 (apoA1) and B (apoB) are important protective factors and risk factors, respectively, for atherosclerosis and coronary heart disease. It is well known that both apoA1 and apoB reveal strong familial aggregation. Our goal was to investigate whether exogenous variables influe...

journal_title：Statistics in medicine

authors： Ziegler A,Kastner C,Brunner D,Blettner M

更新日期：2000-12-30 00:00:00

abstract：:The effective dose (ED) is the pharmaceutical dosage required to produce a therapeutic response in a fixed proportion of the patients. When only one drug is considered, the problem is a univariate one and has been well-studied. However, in the multidimensional setting, that is, in the presence of combinations of agent...

journal_title：Statistics in medicine

authors： Jankowski H,Ji X,Stanberry L

更新日期：2014-10-30 00:00:00

abstract：:Researchers in clinical science and bioinformatics frequently aim to learn which of a set of candidate biomarkers is important in determining a given outcome, and to rank the contributions of the candidates accordingly. This article introduces a new approach to research questions of this type, based on targeted maximu...

journal_title：Statistics in medicine

authors： Bembom O,Petersen ML,Rhee SY,Fessel WJ,Sinisi SE,Shafer RW,van der Laan MJ

更新日期：2009-01-15 00:00:00

abstract：:Residuals in normal regression are used to assess a model's goodness-of-fit (GOF) and discover directions for improving the model. However, there is a lack of residuals with a characterized reference distribution for censored regression. In this article, we propose to diagnose censored regression with normalized rando...

journal_title：Statistics in medicine

authors： Li L,Wu T,Feng C

更新日期：2020-12-13 00:00:00

abstract：:Modelling disease clustering over space and time can be helpful in providing indications of possible exposures and planning corresponding public health practices. Though a considerable number of studies focus on modelling spatio-temporal patterns of disease, most of them do not directly model a spatio-temporal cluster...

journal_title：Statistics in medicine

authors： Yan P,Clayton MK

更新日期：2006-03-15 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

abstract：:Competing compartment models of different complexities have been used for the quantitative analysis of dynamic contrast-enhanced magnetic resonance imaging data. We present a spatial elastic net approach that allows to estimate the number of compartments for each voxel such that the model complexity is not fixed a pri...

journal_title：Statistics in medicine

authors： Sommer JC,Gertheiss J,Schmid VJ

更新日期：2014-03-15 00:00:00

abstract：:In studies with survival or time-to-event outcomes, a competing risk is an event whose occurrence precludes the occurrence of the primary event of interest. Specialized statistical methods must be used to analyze survival data in the presence of competing risks. We conducted a review of randomized controlled trials wi...

journal_title：Statistics in medicine

authors： Austin PC,Fine JP

更新日期：2017-04-15 00:00:00

abstract：:Although there are many models which are used to calculate the health benefits (and thus the cost-effectiveness) of vaccination programmes, they can be divided into two groups: those which assume a constant force of infection, that is a constant per-susceptible rate of infection; and those which assume that the force ...

journal_title：Statistics in medicine

authors： Edmunds WJ,Medley GF,Nokes DJ

更新日期：1999-12-15 00:00:00

abstract：:To study the spread of sexually transmitted diseases (STDs) using social/sexual mixing models, one must have quantitative information about sexual mixing. An unavoidable complication in gathering such information by survey is that members of the surveyed population will almost certainly have sexual contacts outside th...

journal_title：Statistics in medicine

authors： Rubin G,Umbach D,Shyu SF,Castillo-Chavez C

更新日期：1992-09-15 00:00:00

abstract：:In medical and health studies, heterogeneities in clustered count data have been traditionally modeled by positive random effects in Poisson mixed models; however, excessive zeros often occur in clustered medical and health count data. In this paper, we consider a three-level random effects zero-inflated Poisson model...

journal_title：Statistics in medicine

authors： Ma R,Hasan MT,Sneddon G

更新日期：2009-08-15 00:00:00

abstract：:Genome-wide association studies are characterized by a huge number of statistical tests performed to discover new disease-related genetic variants [in the form of single-nucleotide polymorphisms (SNPs)] in human DNA. Many SNPs have been identified for cross-sectionally measured phenotypes. However, there is a growing ...

journal_title：Statistics in medicine

authors： Sikorska K,Rivadeneira F,Groenen PJ,Hofman A,Uitterlinden AG,Eilers PH,Lesaffre E

更新日期：2013-01-15 00:00:00