A comparison of methods for determining HIV viral set point.

abstract：:Models for infant growth have usually been based on parametric forms, commonly an exponential or similar model, which have been shown to fit poorly especially during the first year of life. An alternative approach is to use a non-parametric model, based on a shape invariant model (SIM), where a single function is tran...

journal_title：Statistics in medicine

authors： Beath KJ

更新日期：2007-05-30 00:00:00

abstract：:We consider a general model for anomaly detection in a longitudinal cohort mortality pattern based on logistic joinpoint regression with unknown joinpoints. We discuss backward and forward sequential procedures for selecting both the locations and the number of joinpoints. Estimation of the model parameters and the se...

journal_title：Statistics in medicine

authors： Czajkowski M,Gill R,Rempala G

更新日期：2008-04-30 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：:A Non-Parametric Maximum Likelihood approach to the estimation of relative risks in the context of disease mapping is discussed and a NPML approximation to conditional autoregressive models is proposed. NPML estimates have been compared to other proposed solutions (Maximum Likelihood via Monte Carlo Scoring, Hierarchi...

journal_title：Statistics in medicine

authors： Biggeri A,Marchi M,Lagazio C,Martuzzi M,Böhning D

更新日期：2000-09-15 00:00:00

abstract：:The cost and efficiency of training clinical centre staff and of duplicate data entry in clinical trials is reviewed. Training is an essential component of quality assurance programmes and it is usually carried out at regular intervals in long-term clinical trials. Initial training of staff and regular retraining is i...

journal_title：Statistics in medicine

authors： Neaton JD,Duchene AG,Svendsen KH,Wentworth D

更新日期：1990-01-01 00:00:00

abstract：:A new method is proposed for the surveillance of Down's syndrome among newborn. Despite the strong dependence of overall risk of Down's syndrome on maternal age, it has been suggested that an environmentally induced increase in risk may be additive over all maternal ages. The surveillance method introduced here is spe...

journal_title：Statistics in medicine

authors： Lie RT,Heuch I,Irgens LM

更新日期：1993-01-15 00:00:00

abstract：:Exploring the possible reasons for heterogeneity between studies is an important aspect of conducting a meta-analysis. This paper compares a number of methods which can be used to investigate whether a particular covariate, with a value defined for each study in the meta-analysis, explains any heterogeneity. The main ...

journal_title：Statistics in medicine

authors： Thompson SG,Sharp SJ

更新日期：1999-10-30 00:00:00

abstract：:For patients who were previously treated for prostate cancer, salvage hormone therapy is frequently given when the longitudinal marker prostate-specific antigen begins to rise during follow-up. Because the treatment is given by indication, estimating the effect of the hormone therapy is challenging. In a previous pape...

journal_title：Statistics in medicine

authors： Taylor JM,Shen J,Kennedy EH,Wang L,Schaubel DE

更新日期：2014-01-30 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 comparing two treatments under a typical sequential clinical trial setting, a 50-50 randomization design generates reliable data for making efficient inferences about the treatment difference for the benefit of patients in the general population. However, if the treatment difference is large and the endpoint of the...

journal_title：Statistics in medicine

authors： Yao Q,Wei LJ

更新日期：1996-11-15 00:00:00

abstract：:Longitudinal studies collect information on a sample of individuals which is followed over time to analyze the effects of individual and time-dependent characteristics on the observed response. These studies often suffer from attrition: individuals drop out of the study before its completion time and thus present inco...

journal_title：Statistics in medicine

authors： Alfò M,Maruotti A

更新日期：2009-08-30 00:00:00

abstract：:Funnel plots are widely used to visualize grouped data, for example, in institutional comparison. This paper extends the concept to a multi-level setting, displaying one level at a time, adjusted for the other levels, as well as for covariates at all levels. These level-adjusted funnel plots are based on a Markov chai...

journal_title：Statistics in medicine

authors： Lindhagen L,Darkahi B,Sandblom G,Berglund L

更新日期：2014-09-20 00:00:00

abstract：:Dependence between observations on a dichotomous variable renders invalid the usual chi-square tests of independence and inflates the variances of parameter estimates. Such a situation occurs, for example, when subjects consist of members of the same family or with repeated observations on the same person. In this pap...

journal_title：Statistics in medicine

authors： Donald A,Donner A

更新日期：1987-06-01 00:00:00

abstract：:The identification of changes in the recent trend is an important issue in the analysis of cancer mortality and incidence data. We apply a joinpoint regression model to describe such continuous changes and use the grid-search method to fit the regression function with unknown joinpoints assuming constant variance and ...

journal_title：Statistics in medicine

authors： Kim HJ,Fay MP,Feuer EJ,Midthune DN

更新日期：2000-02-15 00:00:00

abstract：:In natural history studies of chronic disease, it is of interest to understand the evolution of key variables that measure aspects of disease progression. This is particularly true for immunological variables among persons infected with the human immunodeficiency virus (HIV). The natural time scale for such studies is...

journal_title：Statistics in medicine

authors： Vittinghoff E,Malani HM,Jewell NP

更新日期：1994-06-15 00:00:00

abstract：:Correct specification of the inverse probability weighting (IPW) model is necessary for consistent inference from a marginal structural Cox model (MSCM). In practical applications, researchers are typically unaware of the true specification of the weight model. Nonetheless, IPWs are commonly estimated using parametric...

journal_title：Statistics in medicine

authors： Karim ME,Platt RW,BeAMS study group.

更新日期：2017-06-15 00:00:00

abstract：:Given N points or events occurring according to some probability distribution in the unit interval (0, 1), the simple scan statistic is defined to be the maximum number of points in any sub-interval of length d. In many areas, as in epidemiology, it is used to test the null hypothesis that the events are random, again...

journal_title：Statistics in medicine

authors： Nagarwalla N

更新日期：1996-04-15 00:00:00

abstract：:Assessment of equivalence or non-inferiority in accuracy between two diagnostic procedures often involves comparisons of paired areas under the receiver operating characteristic (ROC) curves. With some pre-specified clinically meaningful limits, the current approach to evaluating equivalence is to perform the two one-...

journal_title：Statistics in medicine

authors： Liu JP,Ma MC,Wu CY,Tai JY

更新日期：2006-04-15 00:00:00

abstract：:Health surveillance involves collecting public health data on chronic and infectious diseases to detect changes in disease incidence rates in order to improve public health. Timely detection of disease clusters is essential in prospective public health surveillance. Most existing health surveillance research is based ...

journal_title：Statistics in medicine

authors： Jiang W,Han SW,Tsui KL,Woodall WH

更新日期：2011-02-28 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：:In multiple-record systems estimation it is usually assumed that all registration relate to the same population. In this paper, we develop a method which can be used when the registrations relate to different populations, in the sense that they cover, for example, different time periods or regions. We show that under ...

journal_title：Statistics in medicine

authors： Zwane EN,van der Pal-de Bruin K,van der Heijden PG

更新日期：2004-07-30 00:00:00

abstract：:Summarizing the information of many studies using a meta-analysis becomes more and more important, also in the field of diagnostic studies. The special challenge in meta-analysis of diagnostic accuracy studies is that in general sensitivity and specificity are co-primary endpoints. Across the studies both endpoints ar...

journal_title：Statistics in medicine

authors： Zapf A,Hoyer A,Kramer K,Kuss O

更新日期：2015-12-20 00:00:00

abstract：:Clinical trials utilizing predictive biomarkers have become a research focus in personalized medicine. We investigate the effects of biomarker misclassification on the design and analysis of stratified biomarker clinical trials. For a variety of inference problems including marker-treatment interaction in particular, ...

journal_title：Statistics in medicine

authors： Liu C,Liu A,Hu J,Yuan V,Halabi S

更新日期：2014-08-15 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：:In a longitudinal study of workers in seven Norwegian aluminium plants, the time to development of asthmatic symptoms could only be determined to lie in the interval between two consecutive health examinations. In a previous paper we analysed the data by survival techniques for interval censored data. In the present p...

journal_title：Statistics in medicine

authors： Samuelsen SO,Kongerud J

更新日期：1994-09-15 00:00:00

abstract：:The focus of this paper is dietary intervention trials. We explore the statistical issues involved when the response variable, intake of a food or nutrient, is based on self-report data that are subject to inherent measurement error. There has been little work on handling error in this context. A particular feature of...

journal_title：Statistics in medicine

authors： Keogh RH,Carroll RJ,Tooze JA,Kirkpatrick SI,Freedman LS

更新日期：2016-11-10 00:00:00

abstract：:A new testing approach is described for improving statistical tests of independence in sets of tables stratified on one or more relevant factors in case of categorical (nominal or ordinal) variables. Common tests of independence that exploit the ordinality of one of the variables use a restricted-alternative approach....

journal_title：Statistics in medicine

authors： Iannario M,Lang JB

更新日期：2016-11-10 00:00:00

abstract：:Delay in the outcome variable is challenging for outcome-adaptive randomization, as it creates a lag between the number of subjects accrued and the information known at the time of the analysis. Motivated by a real-life pediatric ulcerative colitis trial, we consider a case where a short-term predictor is available fo...

journal_title：Statistics in medicine

authors： Kim MO,Liu C,Hu F,Lee JJ

更新日期：2014-10-15 00:00:00

abstract：:Biostatistical concepts and methods apply to various problems arising in actual U.S. legal cases. These involve: measures of association, assessing the potential effect of omitted variables and the Peters-Belson approach to regression. In particular, we present the inapplicability of Fisher's exact test in the case wh...

journal_title：Statistics in medicine

authors： Gastwirth JL,Greenhouse SW

更新日期：1995-08-15 00:00:00

abstract：:In time-to-event analysis, the traditional summary measures have been based on the hazard function, survival function, quantile event time, restricted mean event time, and residual lifetime. Under competing risks, furthermore, typical summary measures have been the cause-specific hazard function and cumulative inciden...

journal_title：Statistics in medicine

authors： Jia Y,Jeong JH

更新日期：2021-01-06 00:00:00