Abstract:
:Among many other uses, positron emission tomography (PET) can be used in studies to estimate the density of a neuroreceptor at each location throughout the brain by measuring the concentration of a radiotracer over time and modeling its kinetics. There are a variety of kinetic models in common usage and these typically rely on nonlinear least-squares (LS) algorithms for parameter estimation. However, PET data often contain artifacts (such as uncorrected head motion) and so the assumptions on which the LS methods are based may be violated. Quantile regression (QR) provides a robust alternative to LS methods and has been used successfully in many applications. We consider fitting various kinetic models to PET data using QR and study the relative performance of the methods via simulation. A data adaptive method for choosing between LS and QR is proposed and the performance of this method is also studied.
journal_name
Stat Medjournal_title
Statistics in medicineauthors
Chang C,Ogden RTdoi
10.1002/sim.3510subject
Has Abstractpub_date
2009-03-15 00:00:00pages
1004-16issue
6eissn
0277-6715issn
1097-0258journal_volume
28pub_type
杂志文章abstract::The weighted average treatment effect is a causal measure for the comparison of interventions in a specific target population, which may be different from the population where data are sampled from. For instance, when the goal is to introduce a new treatment to a target population, the question is what efficacy (or ef...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.7980
更新日期:2019-02-10 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::To benefit Alzheimer's disease research, a central data co-ordinating centre (CDCC) is planned that will systematically collect data from 27 Alzheimer's disease centres (ADCs) located nationwide. This CDCC will combine, analyse and disseminate epidemiologic, demographic, clinical and neuropathological data to research...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/(sici)1097-0258(20000615/30)19:11/12<1453:
更新日期:2000-06-15 00:00:00
abstract::Ordinal data appear in a wide variety of scientific fields. These data are often analyzed using ordinal logistic regression models that assume proportional odds. When this assumption is not met, it may be possible to capture the lack of proportionality using a constrained structural relationship between the odds and t...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.5689
更新日期:2013-06-15 00:00:00
abstract::Vaccination in populations can have several kinds of effects. Establishing that vaccination produces population-level effects beyond the direct effects in the vaccinated individuals can have important consequences for public health policy. Formal methods have been developed for study designs and analysis that can esti...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.7392
更新日期:2018-01-30 00:00:00
abstract::In contrast to other models for ordinal data, the continuation ratio model can be fitted with standard statistical software. This makes it particularly appropriate for large clinical trials with ordinal response variables. In addition, when the trials are longitudinal, this model can be applied to individual responses...
journal_title:Statistics in medicine
pub_type: 临床试验,杂志文章,随机对照试验
doi:10.1002/(sici)1097-0258(19971230)16:24<2873::aid-s
更新日期:1997-12-30 00:00:00
abstract::We develop a simulation-based procedure for determining the required sample size in binomial regression risk assessment studies when response data are subject to misclassification. A Bayesian average power criterion is used to determine a sample size that provides high probability, averaged over the distribution of po...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.3505
更新日期:2009-02-28 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
pub_type: 杂志文章
doi:10.1002/sim.4780120104
更新日期:1993-01-15 00:00:00
abstract::Sequential analysis is frequently employed to address ethical and financial issues in clinical trials. Sequential analysis may be performed using standard group sequential designs, or, more recently, with adaptive designs that use estimates of treatment effect to modify the maximal statistical information to be collec...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.4156
更新日期:2011-05-20 00:00:00
abstract::In phase 3 clinical trials, ethical and financial concerns motivate sequential analyses in which the data are analyzed prior to completion of the entire planned study. Existing group sequential software accounts for the effects of these interim analyses on the sampling density by assuming that the contribution of subs...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.6306
更新日期:2014-12-20 00:00:00
abstract::Clinical prediction models (CPMs) can inform decision making about treatment initiation, which requires predicted risks assuming no treatment is given. However, this is challenging since CPMs are usually derived using data sets where patients received treatment, often initiated postbaseline as "treatment drop-ins." Th...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.7913
更新日期:2018-12-10 00:00:00
abstract::Methodology for the meta-analysis of individual patient data with survival end-points is proposed. Motivated by questions about the reliance on hazard ratios as summary measures of treatment effects, a parametric approach is considered and percentile ratios are introduced as an alternative to hazard ratios. The genera...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.4086
更新日期:2010-12-20 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
pub_type: 杂志文章
doi:10.1002/sim.7195
更新日期:2017-03-15 00:00:00
abstract::When designing a study to develop a new prediction model with binary or time-to-event outcomes, researchers should ensure their sample size is adequate in terms of the number of participants (n) and outcome events (E) relative to the number of predictor parameters (p) considered for inclusion. We propose that the mini...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.7992
更新日期:2019-03-30 00:00:00
abstract::Reference ranges which take time (such as age) into account are often required in medicine, but simple, systematic and efficient statistical methods for constructing them are lacking. A method is described which is based on low order polynomial curves (linear, quadratic or occasionally cubic), together with guidelines...
journal_title:Statistics in medicine
pub_type: 临床试验,杂志文章,多中心研究
doi:10.1002/sim.4780100502
更新日期:1991-05-01 00:00:00
abstract::In recent years, quality control charts have been increasingly applied in the healthcare environment, for example, to monitor surgical performance. Risk-adjusted cumulative (CUSUM) charts that utilize risk scores like the Parsonnet score to estimate the probability of death of a patient from an operation turn out to b...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.8104
更新日期:2019-05-30 00:00:00
abstract::Meta-analysis to investigate the joint effect of multiple factors in the aetiology of a disease is of increasing importance in epidemiology. This task is often challenging in practice, because studies typically concentrate on studying the effect of only one exposure, sometimes may report the interaction between two ex...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.2689
更新日期:2006-12-30 00:00:00
abstract::I reflect on the statistical methods of the Christakis-Fowler studies on network-based contagion of traits by checking the sensitivity of these kinds of results to various alternate specifications and generative mechanisms. Despite the honest efforts of all involved, I remain pessimistic about establishing whether bin...
journal_title:Statistics in medicine
pub_type: 评论,杂志文章
doi:10.1002/sim.5551
更新日期:2013-02-20 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
pub_type: 杂志文章
doi:10.1002/sim.8830
更新日期:2021-01-15 00:00:00
abstract::Diseases can be interconnected. In the recent years, there has been a surge of multidisease studies. Among them, HDN (human disease network) analysis takes a system perspective, examines the interconnections among diseases along with their individual properties, and has demonstrated great potential. Most of the existi...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.8472
更新日期:2020-04-30 00:00:00
abstract::Subjects in randomized controlled trials do not always comply to the treatment condition they have been assigned to. This may cause the estimated effect of the intervention to be biased and also affect efficiency, coverage of confidence intervals, and statistical power. In cluster randomized trials non-compliance may ...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.8351
更新日期:2019-11-20 00:00:00
abstract::Measures that quantify the impact of heterogeneity in univariate meta-analysis, including the very popular I(2) statistic, are now well established. Multivariate meta-analysis, where studies provide multiple outcomes that are pooled in a single analysis, is also becoming more commonly used. The question of how to quan...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.5453
更新日期:2012-12-20 00:00:00
abstract::Studies involving longitudinal binary responses are widely applied in the health and biomedical sciences research and frequently analyzed by generalized estimating equations (GEE) method. This article proposes an alternative goodness-of-fit test based on the nonparametric smoothing approach for assessing the adequacy ...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.3315
更新日期:2008-09-30 00:00:00
abstract::In modern observational studies using electronic health records or other routinely collected data, both the outcome and covariates of interest can be error-prone and their errors often correlated. A cost-effective solution is the two-phase design, under which the error-prone outcome and covariates are observed for all...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.8799
更新日期:2021-02-10 00:00:00
abstract::In many biomedical and epidemiological studies, data are often clustered due to longitudinal follow up or repeated sampling. While in some clustered data the cluster size is pre-determined, in others it may be correlated with the outcome of subunits, resulting in informative cluster size. When the cluster size is info...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.4239
更新日期:2011-07-10 00:00:00
abstract::We describe the usual statistical concepts and consequent appropriate simulations of a prospective study for the simple case of a single risk variable and an assumed logistic model. We examine the simulations of Lilienfeld and Pyne, and show that they are seriously flawed. Contrary to those authors' claims, the estima...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.4780040212
更新日期:1985-04-01 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
pub_type: 杂志文章
doi:10.1002/sim.7006
更新日期:2016-11-10 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
pub_type: 杂志文章
doi:10.1002/1097-0258(20000915/30)19:17/18<2539::aid-s
更新日期:2000-09-15 00:00:00
abstract::We consider the problem of identifying subgroups of participants in a clinical trial that have enhanced treatment effect. Recursive partitioning methods that recursively partition the covariate space based on some measure of between groups treatment effect difference are popular for such subgroup identification. The m...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.8214
更新日期:2019-09-20 00:00:00
abstract::In this paper the following problem of clinical research is explored. Several potential new treatments are available for use against a certain disease. These are evaluated in a series of pilot studies which will constitute phase II clinical trials. The most promising will then be compared with a standard treatment in ...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.4780050510
更新日期:1986-09-01 00:00:00