Abstract:
:In this paper, we consider pooling schemes in which samples are to be tested in two-stages. We show that when batch size is limited as well as pool size, selection schemes tend to be more efficient and flexible. Formulae for the efficiencies of square arrays in all dimensions and for all selection schemes are given in the Appendix. A Fortran program has been written to find whether the most efficient scheme under constraints of batch and pool size be 'square' or 'selection'.
journal_name
Stat Medjournal_title
Statistics in medicineauthors
Sudbury Adoi
10.1002/sim.3965subject
Has Abstractpub_date
2010-09-20 00:00:00pages
2194-9issue
21eissn
0277-6715issn
1097-0258journal_volume
29pub_type
杂志文章abstract::Comparative studies of the accuracy of diagnostic procedures often use a paired design to gain in efficiency. Standard methods for analysing data from paired designs require complete observations. In many studies, however, one of the test results may be missing for some patients. In this paper, we propose a simple cor...
journal_title:Statistics in medicine
pub_type: 临床试验,杂志文章
doi:10.1002/(SICI)1097-0258(19960815)15:15<1687::AID-S
更新日期:1996-08-15 00:00:00
abstract::When a cancer patient develops a new tumor it is necessary to determine if it is a recurrence (metastasis) of the original cancer, or an entirely new occurrence of the disease. This is accomplished by assessing the histo-pathology of the lesions. However, there are many clinical scenarios in which this pathological di...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.3866
更新日期:2010-07-10 00:00:00
abstract::In many chronic disease processes subjects are at risk of two or more types of events. We describe a bivariate mixed Poisson model in which a copula function is used to model the association between two gamma distributed random effects. The resulting model is a bivariate negative binomial process in which each type of...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.3830
更新日期:2010-03-15 00:00:00
abstract::Confounding is a major concern in observational studies. To adjust for confounding bias, the potential confounder(s) for a study must first be identified and measured. But this is not always possible. The unmeasured factors may also exhibit effect modification, and this further complicates the situation. In this paper...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.4151
更新日期:2011-04-30 00:00:00
abstract::We construct nonparametric regression estimators of a number of temporal functions in a multistate system based on a continuous univariate baseline covariate. These estimators include state occupation probabilities, state entry, exit, and waiting (sojourn) time distribution functions of a general progressive (e.g., ac...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.5703
更新日期:2013-07-30 00:00:00
abstract::Observational cohort studies often feature longitudinal data subject to irregular observation. Moreover, the timings of observations may be associated with the underlying disease process and must thus be accounted for when analysing the data. This paper suggests that multiple outputation, which consists of repeatedly ...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.6829
更新日期:2016-05-20 00:00:00
abstract::We extend the shared frailty model of recurrent events and a dependent terminal event to allow for a nonparametric covariate function. We include a Gaussian random effect (frailty) in the intensity functions of both the recurrent and terminal events to capture correlation between the two processes. We employ the penal...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.4297
更新日期:2011-09-30 00:00:00
abstract::We present some practical extensions and applications of a strategy proposed by Thall, Simon and Estey for designing and monitoring single-arm clinical trials with multiple outcomes. We show by application how the strategy may be applied to construct designs for phase IIA activity trials and phase II equivalence trial...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/(sici)1097-0258(19980730)17:14<1563::aid-s
更新日期:1998-07-30 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::A method is proposed to infer the randomized treatment effect on survival after an adjustment for a post-randomization variable. The post-randomization variable is made independent of the treatment assignment and is considered a surrogate for baseline prognostic factors. The relationship between the post-randomization...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.968
更新日期:2001-11-30 00:00:00
abstract::Down's syndrome screening is currently carried out using a combination of biochemical markers measured in maternal serum samples; these include MSAFP, Total hCG, uE3 and Free beta-hCG. Recently a number of papers have compared the effectiveness of different combinations of these markers. Some recommend MSAFP, Total hC...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/(sici)1097-0258(19970715)16:13<1481::aid-s
更新日期:1997-07-15 00:00:00
abstract::Repeated cross-sectional samples are common in national surveys of health like the National Health Interview Survey (NHIS). Because population health outcomes generally evolve slowly, pooling data across years can improve the precision of current-year annual estimates of disease prevalence and other health outcomes. P...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.3897
更新日期:2011-02-28 00:00:00
abstract::The power to detect a treatment effect in cluster randomized trials can be increased by increasing the number of clusters. An alternative is to include covariates into the regression model that relates treatment condition to outcome. In this paper, formulae are derived in order to evaluate both strategies on basis of ...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.2297
更新日期:2006-08-15 00:00:00
abstract::Austin Bradford Hill was once a friend to The Lancet, but, as occasionally happens, friends fall out. The great legacy of his association with the journal, however, was Principles of Medical Statistics. As each edition was succeeded by another--the first in 1937, the last in 1991--he seemed to shift his view about the...
journal_title:Statistics in medicine
pub_type: 传
doi:10.1002/1097-0258(20001215)19:23<3149::aid-sim617>
更新日期:2000-12-15 00:00:00
abstract::In vaccine safety studies, subjects are considered at increased risk for adverse events for a period of time after vaccination known as risk window. To our knowledge, risk windows for vaccine safety studies have tended to be pre-defined and not to use information from the current study. Inaccurate specification of the...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.4125
更新日期:2011-03-30 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::A new goodness-of-fit test for the logistic regression model is proposed. It exploits the property of this model that when it is correct, i.e. not misspecified, the parameter estimates are (asymptotically) invariant under reweighting the observations by weights wi that are a function of the binary (0/1) outcomes yi. M...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.1997
更新日期:2005-01-15 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::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
pub_type: 杂志文章
doi:10.1002/sim.4780060408
更新日期:1987-06-01 00:00:00
abstract::Optimal prevention and treatment strategies for a disease of multiple causes, such as pneumonia, must be informed by the population distribution of causes among cases, or cause-specific case fractions (CSCFs). CSCFs may further depend on additional explanatory variables. Existing methodological literature in disease e...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.8804
更新日期:2021-02-20 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
pub_type: 杂志文章,多中心研究
doi:10.1002/sim.4780121707
更新日期:1993-09-15 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::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
pub_type: 杂志文章
doi:10.1002/sim.4780141505
更新日期:1995-08-15 00:00:00
abstract::The purpose of this research was to develop appropriate methods for analysing repeated ordinal categorical data that arose in an intervention trial to prevent oesophageal cancer. The measured response was the degree of oesophageal dysplasia at 2.5 and 6 years after randomization. An important feature was that some res...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.4780130511
更新日期:1994-03-15 00:00:00
abstract::Teaching statistics to medical students is a challenging and often unrewarding task. However, few would argue the need for statistics in the medical school curriculum. In recent years, there has been a growing call for teaching only statistical concepts in medical schools. We strongly oppose this opinion and offer an ...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.2906
更新日期:2007-10-15 00:00:00
abstract::Comparative Poisson trials of prophylactic interventions, such as vaccines, can be lengthy and costly. We evaluate two easily implemented approaches to reduce numbers of disease cases and person years of follow up (N(u+t)) for comparative Poisson trials with fixed numbers of cases (T); (i) altering k the portion of N(...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.1724
更新日期:2004-04-30 00:00:00
abstract::The original article to which this Correction refers was published in Statistics in Medicine 2000 19(14): 1901-1914. ...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/1097-0258(20001115)19:21<3017::aid-sim785>
更新日期:2000-11-15 00:00:00
abstract::The problem of evaluating an averaged functional magnetic resonance imaging (fMRI) response for repeated block design experiments was considered within a semiparametric regression model with autocorrelated residuals. We applied functional data analysis (FDA) techniques that use a least-squares fitting of B-spline expa...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.2981
更新日期:2007-09-20 00:00:00
abstract::Propensity score analysis is widely used in observational studies to adjust for confounding and estimate the causal effect of a treatment on the outcome. When the outcome is survival time, there are special considerations on the definition of the causal estimand, point, and variance estimation that have not been thoro...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.7839
更新日期:2018-11-20 00:00:00
abstract::Standard approaches to analysis of randomized controlled trials (RCTs) using Markov models make it difficult to generalize treatment effects to new patient groups and synthesize evidence across trials. This paper demonstrates how pair-wise and mixed treatment comparison meta-analysis can be applied to event history da...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.4059
更新日期:2011-01-30 00:00:00