Abstract:
:We applied a two-stage random effects model to pulmonary function data from 31 sarcoidosis patients to illustrate its usefulness in analysing unbalanced longitudinal data. For the first stage, repeated measurements of percentage of predicted forced vital capacity (FVC%) from an individual were modelled as a function of time since initial clinical assessment. At the second stage, parameters of this function were modelled as a function of certain patient characteristics. We used three methods for estimating the model parameters: maximum likelihood; empirical Bayes; and a two-step least-squares procedure. Similar results were obtained from each, but we recommend the empirical Bayes, since it provides unbiased estimates of variance components. Results indicated that deterioration in FVC% is associated with a higher initial FVC% value and large numbers of both total cells and eosinophils in bronchoalveolar lavage at the initial assessment. Improvement is associated with higher values of pulmonary Gallium uptake at initial assessment and race. Blacks are more likely to improve than whites.
journal_name
Stat Medjournal_title
Statistics in medicineauthors
Vacek PM,Mickey RM,Bell DYdoi
10.1002/sim.4780080206subject
Has Abstractpub_date
1989-02-01 00:00:00pages
189-200issue
2eissn
0277-6715issn
1097-0258journal_volume
8pub_type
杂志文章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::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
pub_type: 杂志文章
doi:10.1002/sim.8852
更新日期:2020-12-13 00:00:00
abstract::In case-control studies, the Cochran-Armitage (CA) trend test is powerful for detection of an association between a risk allele and a marker. To apply this test, a score should be assigned to the genotypes based on the genetic model. When the underlying genetic model is unknown, the trend test statistic is a function ...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.1474
更新日期:2003-08-30 00:00:00
abstract::Health questionnaires are often built up from sets of questions that are totaled to obtain a sum score. An important consideration in designing questionnaires is to minimize respondent burden. An increasingly popular method for efficient measurement is computerized adaptive testing; unfortunately, many health question...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.5936
更新日期:2014-02-10 00:00:00
abstract::In this paper, we develop a method for the simultaneous estimation of spectral density functions (SDFs) for a collection of stationary time series that share some common features. Due to the similarities among the SDFs, the log-SDF can be represented using a common set of basis functions. The basis shared by the colle...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.7972
更新日期:2018-12-30 00:00:00
abstract::Clinical trials of treatments for rare or fatal diseases must often use historical rather than randomized concurrent controls. Randomized trials may not be possible if (1) the number of patients available is quite small, (2) ethical considerations discourage the assignment of patients to control treatments known to be...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.4780030305
更新日期:1984-07-01 00:00:00
abstract::This paper investigates the impact on area life tables of the specification of unobserved frailty. Frailty specification may affect both the regression effects of area and individual level covariates, and lead to changes in the value of summary mortality parameters, such as life expectancy. The paper also investigates...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.4780141703
更新日期:1995-09-15 00:00:00
abstract::Girardeau, Ravaud and Donner in 2008 presented a formula for sample size calculations for cluster randomised crossover trials, when the intracluster correlation coefficient, interperiod correlation coefficient and mean cluster size are specified in advance. However, in many randomised trials, the number of clusters is...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.8191
更新日期:2019-08-15 00:00:00
abstract::Assessing and comparing the performance of correlated predictive scores are of current interest in precision medicine. Given the limitations of available theoretical approaches for assessing and comparing the predictive accuracy, numerical methods are highly desired which, however, have not been systematically develop...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.8566
更新日期:2020-09-10 00:00:00
abstract::This paper reviews several emerging and recurrent issues relating to the drug development process. These emerging issues include changes to the FDA regulatory environment, internationalization of drug development, advances in computer technology and visualization tools, and efforts to incorporate meta-analysis methodo...
journal_title:Statistics in medicine
pub_type: 杂志文章,评审
doi:10.1002/(sici)1097-0258(19990915/30)18:17/18<2301:
更新日期:1999-09-15 00:00:00
abstract::Longitudinal biomarker data are often collected in studies, providing important information regarding the probability of an outcome of interest occurring at a future time. With many new and evolving technologies for biomarker discovery, the number of biomarker measurements available for analysis of disease progression...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.8687
更新日期:2020-11-20 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::In longitudinal studies, missing observations occur commonly. It has been well known that biased results could be produced if missingness is not properly handled in the analysis. Authors have developed many methods with the focus on either incomplete response or missing covariate observations, but rarely on both. The ...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.5536
更新日期:2013-02-28 00:00:00
abstract::The EQ-5D, a widely used multiattribute utility instrument, is commonly used in health economic evaluations where the goal is to decide on which treatments to reimburse. Like other instruments, value sets of the EQ-5D are constructed using valuation studies typically valuing a subset of the health states and using pre...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.8592
更新日期:2020-10-15 00:00:00
abstract::Blinded estimation of variance allows for changing the sample size without compromising the integrity of the trial. Some of the methods that estimate the variance in a blinded manner either make untenable assumptions or are only applicable to two-treatment trials. We propose a new method for continuous endpoints that ...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.2070
更新日期:2005-06-30 00:00:00
abstract::This paper is a compendium of exact and asymptotic formulae and tables for estimating the sample size in a clinical trial with two treatment groups and a dichotomous outcome. The paper provides separate formulae for equal and unequal treatment group sizes, formulae for the calculation of power given the sample size, a...
journal_title:Statistics in medicine
pub_type: 杂志文章,评审
doi:10.1002/(SICI)1097-0258(19960115)15:1<1::AID-SIM13
更新日期:1996-01-15 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::In medical research, a two-phase study is often used for the estimation of the area under the receiver operating characteristic curve (AUC) of a diagnostic test. However, such a design introduces verification bias. One of the methods to correct verification bias is inverse probability weighting (IPW). Since the probab...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.8700
更新日期:2020-11-30 00:00:00
abstract::This paper discusses the benefits and limitations of adaptive sample size re-estimation for phase 3 confirmatory clinical trials. Comparisons are made with more traditional fixed sample and group sequential designs. It is seen that the real benefit of the adaptive approach arises through the ability to invest sample s...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.4102
更新日期:2011-12-10 00:00:00
abstract::We present a model for describing correlated binocular data from reader-based diagnostic studies, where the same group of readers evaluates the presence or absence of certain diseases on binocular organs (e.g., fellow eyes) of patients. Multiple random effects are incorporated to meaningfully delineate various associa...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.6584
更新日期:2015-12-20 00:00:00
abstract::In the comparison of two or more treatment groups to a control group, consider a study with non-decreasing repeated measurements of the same characteristic taken over a common set of time points for each subject. Based on the vector of possibly incomplete responses from each subject, this paper considers asymptoticall...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/(SICI)1097-0258(19961215)15:23<2509::AID-S
更新日期:1996-12-15 00:00:00
abstract::Estimates of transmission probabilities for sexually transmitted diseases historically come from studies of uninfected individuals exposed to those with a high disease prevalence (for example, prostitutes). However, changes in sexual behaviour, much of which relates to concerns about AIDS, has made identification of p...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.4780110502
更新日期:1992-03-01 00:00:00
abstract::A study of long term survival of 1487 patients given an allogeneic bone marrow transplant for acute myelogenous leukaemia and 729 patients given a transplant for severe aplastic anaemia was conducted by the International Bone Marrow Transplant Registry. One aim of this study is to determine if the mortality rates of t...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/(sici)1097-0258(19990630)18:12<1529::aid-s
更新日期:1999-06-30 00:00:00
abstract::Many epidemiologic investigations are designed to study the effects of multiple exposures. Most of these studies are analysed either by fitting a risk-regression model with all exposures forced in the model, or by using a preliminary-testing algorithm, such as stepwise regression, to produce a smaller model. Research ...
journal_title:Statistics in medicine
pub_type: 杂志文章,评审
doi:10.1002/sim.4780120802
更新日期:1993-04-30 00:00:00
abstract::The sample size required for a cluster randomised trial is inflated compared with an individually randomised trial because outcomes of participants from the same cluster are correlated. Sample size calculations for longitudinal cluster randomised trials (including stepped wedge trials) need to take account of at least...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.7028
更新日期:2016-11-20 00:00:00
abstract::The aim of this paper is to demonstrate the effect of excluding incomplete observations and competing events when calculating cross-sectional measures of NHS waiting times, and to obtain a more accurate estimate of the 'time-to-admission' of those listed on NHS waiting lists using life-table methods. The official 'tim...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/1097-0258(20000815)19:15<2037::aid-sim606>
更新日期:2000-08-15 00:00:00
abstract::Subjective judgements of complex variables are commonly recorded as ordered categorical data. The rank-invariant properties of such data are well known, and there are various statistical approaches to the analysis and modelling of ordinal data. This paper focuses on the non-additive property of ordered categorical dat...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/(sici)1097-0258(19981230)17:24<2923::aid-s
更新日期:1998-12-30 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::We develop parametric maximum likelihood methods to adjust for treatment changes during follow-up in order to assess the causal effect of treatment in clinical trials with time-to-event outcomes. The accelerated failure time model of Robins and Tsiatis relates each observed event time to the underlying event time that...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.1618
更新日期:2004-02-28 00:00:00
abstract::Often in randomized clinical trials and observational studies in occupational and environmental health, a non-negative continuously distributed response variable denoting some metabolites of environmental toxicants is measured in treatment and control groups. When observations occur in both unexposed and exposed subje...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.3170
更新日期:2008-06-15 00:00:00