Abstract:
:Novel methodology is implemented to assess the predictive power of covariate information associated with sequential binary events. Logistic models are first fitted on the basis of a subset of the observations and then evaluated sequentially on the rest. The probabilistic forecasts are compared to the outcomes via a scoring function, but as most validation samples are small, the usual reference distribution for the test statistics is inadequate. However, bootstrap-based distributions can easily be constructed. The first example pertains to the evaluation of screening tests for major depression. It illustrates that goodness-of-fit and predictive assessments lead to the selection of very different models. The second example deals with the prediction of a major event in the natural history of HIV-induced disease. It shows that this type of analysis can reveal features missed by other approaches.
journal_name
Stat Medjournal_title
Statistics in medicineauthors
Seillier-Moiseiwitsch Fdoi
10.1002/(SICI)1097-0258(19961030)15:20<2149::AID-Ssubject
Has Abstractpub_date
1996-10-30 00:00:00pages
2149-60issue
20eissn
0277-6715issn
1097-0258pii
10.1002/(SICI)1097-0258(19961030)15:20<2149::AID-Sjournal_volume
15pub_type
杂志文章abstract::The generalized estimating equations (GEE) approach is commonly used to model incomplete longitudinal binary data. When drop-outs are missing at random through dependence on observed responses (MAR), GEE may give biased parameter estimates in the model for the marginal means. A weighted estimating equations approach g...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.1241
更新日期:2002-10-30 00:00:00
abstract::Many complex diseases are known to be affected by the interactions between genetic variants and environmental exposures beyond the main genetic and environmental effects. Study of gene-environment (G×E) interactions is important for elucidating the disease etiology. Existing Bayesian methods for G×E interaction studie...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.8434
更新日期:2020-02-28 00:00:00
abstract::The Jimma Infant Survival Differential Longitudinal Study is an Ethiopian study, set up to establish risk factors affecting infant survival and to investigate socio-economic, maternal and infant-rearing factors that contribute most to the child's early survival. Here, a subgroup of about 1500 children born in Jimma to...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/(sici)1097-0258(19990415)18:7<835::aid-sim
更新日期:1999-04-15 00:00:00
abstract::The problem for assessing biosimilarity and drug interchangeability of follow-on biologics (biosimilar products) is studied. Unlike the generic products, the development of biosimilar products is much more complicated because of fundamental differences in functional structures and manufacturing processes. As a result,...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.5571
更新日期:2013-02-10 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
pub_type: 杂志文章
doi:10.1002/sim.7266
更新日期:2017-06-15 00:00:00
abstract::Many models for clinical prediction (prognosis or diagnosis) are published in the medical literature every year but few such models find their way into clinical practice. The reason may be that since in most cases models have not been validated in independent data, they lack generality and/or credibility. In this pape...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.1691
更新日期:2004-03-30 00:00:00
abstract::A three-component, competing-risk mortality model, developed for animal survival data, fits human life table data for all ages over a range of mean life spans from 16 to 74 years. The competing risks are a novel exponentially-decreasing hazard, dominant during immaturity; a constant hazard, dominant during adulthood; ...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.4780020309
更新日期:1983-07-01 00:00:00
abstract::Statistical inference based on correlated count measurements are frequently performed in biomedical studies. Most of existing sample size calculation methods for count outcomes are developed under the Poisson model. Deviation from the Poisson assumption (equality of mean and variance) has been widely documented in pra...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.8378
更新日期:2019-12-10 00:00:00
abstract::Many split-mouth trials are characterized by the pairing of site-specific outcome and baseline data within each segment of a subject's mouth. However when the response variable of interest is binary, methods of statistical analysis for this design are not well developed. In this paper we present several analytic appro...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.2782
更新日期:2007-08-15 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
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::We examine the use of randomization-based inference for analyzing multiarmed randomized clinical trials, including the application of conditional randomization tests to multiple comparisons. The view is taken that the linkage of the statistical test to the experimental design (randomization procedure) should be recogn...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.8418
更新日期:2020-02-20 00:00:00
abstract::Risk prediction models play an important role in prevention and treatment of several diseases. Models that are in clinical use are often refined and improved. In many instances, the most efficient way to improve a successful model is to identify subgroups for which there is a specific biological rationale for improvem...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.6077
更新日期:2014-05-20 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
pub_type: 杂志文章
doi:10.1002/sim.3027
更新日期:2008-03-30 00:00:00
abstract::Sample size planning should reflect the primary objective of a trial. If the primary objective is prediction, the sample size determination should focus on prediction accuracy instead of power. We present formulas for the determination of training set sample size for survival prediction. Sample size is chosen to contr...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.5550
更新日期:2013-02-28 00:00:00
abstract::This paper investigates the Bayesian procedures for comparing proportions. These procedures are especially suitable for accepting (or rejecting) the equivalence of two population proportions. Furthermore the Bayesian predictive probabilities provide a natural and flexible tool in monitoring trials, especially for choo...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.4780140924
更新日期:1995-05-15 00:00:00
abstract::Childhood acute lymphoblastic leukaemia is treated with long-term intensive chemotherapy. During the latter part of the treatment, the maintenance therapy, the patients receive oral doses of two cytostatics. The doses are tailored to blood counts measured on a weekly basis, and the treatment is therefore highly dynami...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.4393
更新日期:2012-02-28 00:00:00
abstract::We present a new method of detection and inference for spatial clusters of a disease. To avoid ad hoc procedures to test for clustering, we have a clearly defined alternative hypothesis and our test statistic is based on the likelihood ratio. The proposed test can detect clusters of any size, located anywhere in the s...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.4780140809
更新日期:1995-04-30 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
pub_type: 杂志文章
doi:10.1002/1097-0258(20001230)19:24<3345::aid-sim829>
更新日期:2000-12-30 00:00:00
abstract::The World Health Organization and collaborating institutions in four developing countries have conducted a multi-centre randomized controlled trial, in which clinics were allocated at random to two antenatal care (ANC) models. These were the standard 'Western' ANC model and a 'new' ANC model consisting of tests, clini...
journal_title:Statistics in medicine
pub_type: 临床试验,杂志文章,随机对照试验
doi:10.1002/1097-0258(20010215)20:3<401::aid-sim801>3.
更新日期:2001-02-15 00:00:00
abstract::Quality of life (QOL) assessment is a key component of many clinical studies and frequently requires the use of single global summary measures that capture the overall balance of findings from a potentially wide-ranging assessment of QOL issues. We propose and evaluate an irregular multilevel latent variable model sui...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.4455
更新日期:2012-05-20 00:00:00
abstract::Machine learning techniques such as classification and regression trees (CART) have been suggested as promising alternatives to logistic regression for the estimation of propensity scores. The authors examined the performance of various CART-based propensity score models using simulated data. Hypothetical studies of v...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.3782
更新日期:2010-02-10 00:00:00
abstract::In this paper statistical methods are proposed to estimate the distribution of a CD4 T-cell number at the time of a clinical AIDS endpoint from serial measurements of CD4 T-cell values in a cohort study. The statistical formulation of the problem is that of survival analysis with interval censored data, but in which t...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.4780131915
更新日期:1994-10-15 00:00:00
abstract::Surrogate endpoint validation has been well established by the meta-analytical correlation-based approach as outlined in the seminal work of Buyse et al. (Biostatistics, 2000). Surrogacy can be assumed if strong associations on individual and study levels can be demonstrated. Alternatively, if an effect on a true endp...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.6778
更新日期:2016-03-30 00:00:00
abstract::We present an estimate of the kappa-coefficient of agreement between two methods of rating based on matched pairs of binary responses and show that the estimate depends on the common intraclass correlation coefficient between the pairs. Via Monte Carlo simulation, we investigate power of the test of significance on ka...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.4780140109
更新日期:1995-01-15 00:00:00
abstract::Conventional seamless phase 2/3 design with fixed sample size determination (SSD) has gained its popularity in oncology drug development due to attractive features such as significantly shortening the development timeline, minimizing sample size, as well as early decision making. However, this design is not immune to ...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.8543
更新日期:2020-08-15 00:00:00
abstract::Knee replacement is the most commonly used surgical treatment for knee arthritis. It has been reported that knee replacement rates vary across both regions and counties. This paper used data from Medicare patients to develop explanations for the variation. One problem with our data is that we do not have patient level...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/(SICI)1097-0258(19960915)15:17<1875::AID-S
更新日期:1996-09-15 00:00:00
abstract::When the accrual rate is low and the treatment period is long, a long observational period is required before information concerning the primary end point, such as binary response, becomes available in the study. Simon's two-stage designs are often employed in Phase II clinical trials to avoid giving patient an ineffe...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.3424
更新日期:2008-12-20 00:00:00
abstract::The most popular model used for survival analysis is the proportional hazards regression model proposed by Cox. This is mainly due to its exceptional simplicity. Nevertheless the fundamental assumption of the Cox model is the proportionality of the hazards. For many applications, however, this assumption is doubtful. ...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.1411
更新日期:2003-04-15 00:00:00
abstract::This paper discusses regression analysis of multivariate current status failure time data (The Statistical Analysis of Interval-censoring Failure Time Data. Springer: New York, 2006), which occur quite often in, for example, tumorigenicity experiments and epidemiologic investigations of the natural history of a diseas...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.3715
更新日期:2009-11-30 00:00:00
abstract::In many studies, interest lies in determining whether members of the study population will undergo a particular event of interest. Such scenarios are often termed 'mover-stayer' scenarios, and interest lies in modelling two sub-populations of 'movers' (those who have a propensity to undergo the event of interest) and ...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.5529
更新日期:2013-02-20 00:00:00