Abstract:
:This paper models monthly AIDS diagnosis counts in terms of smooth secular trend, calendar month effects, and the number of workdays per month. A parameterization of month effects allows separation of true seasonal effects from a linear trend over the calendar year and an arbitrary June effect. There is strong evidence for seasonal patterns, other calendar month effects, and workday effects. Examination of subgroups defined by reporting delay, initial diagnosis, risk group, and region shows evidence for seasonal patterns in some diagnosis groups, for effects due to imputed diagnosis dates, and for effects due to patients' choices of when to seek diagnosis.
journal_name
Stat Medjournal_title
Statistics in medicineauthors
Bacchetti Pdoi
10.1002/sim.4780131905subject
Has Abstractpub_date
1994-10-15 00:00:00pages
1921-31issue
19-20eissn
0277-6715issn
1097-0258journal_volume
13pub_type
杂志文章abstract::The analysis and recognition of disease clustering in space and its representation on a map is an important problem in epidemiology. An approach using mixture models to identify spatial heterogeneity in disease risk and map construction within an empirical Bayes framework is described. Once heterogeneity is detected, ...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/(sici)1097-0258(19960415)15:7/9<919::aid-s
更新日期:1996-04-15 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::In US states with small subpopulations, the observed mortality rates are often zero, particularly among young ages. Because in life tables, death rates are reported mostly on a log scale, zero mortality rates are problematic. To overcome the observed zero death rates problem, appropriate probability models are used. U...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.6385
更新日期:2015-05-20 00:00:00
abstract::Between-community variance or community-by-time variance is one of the key factors driving the cost of conducting group randomized trials, which are often very expensive. We investigated empirically whether between-community variance could be reduced by controlling individual- and/or community-level covariates and ide...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/(sici)1097-0258(19990315)18:5<539::aid-sim
更新日期:1999-03-15 00:00:00
abstract::In the development of a new treatment in oncology, phase II trials play a key role. On the basis of the data obtained during phase II, it is decided whether the treatment should be studied further. Therefore, the decision to be made on the basis of the data of a phase II trial must be as accurate as possible. For ethi...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.5585
更新日期:2012-12-30 00:00:00
abstract:BACKGROUND:It has been recommended that onset of antidepressant action be assessed using survival analyses with assessments taken at least twice per week. However, such an assessment schedule is problematic to implement. The present study assessed the feasibility of comparing onset of action between treatments using a ...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.2309
更新日期:2006-07-30 00:00:00
abstract::Genetic networks for gene expression data are often built by graphical models, which in turn are built from pair-wise correlations of gene expression levels. A key feature of building graphical models is the evaluation of conditional independence of two traits, given other traits. When conditional independence can be ...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.3274
更新日期:2008-08-30 00:00:00
abstract::This paper presents combinatorial (exact) methods that are useful in the analysis of disease cluster data obtained from small environments, such as buildings and neighbourhoods. Maxwell-Boltzmann and Fermi-Dirac occupancy models are compared in terms of appropriateness of representation of disease incidence patterns (...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.4780121906
更新日期:1993-10-01 00:00:00
abstract::This paper concerns using modified weighted Schoenfeld residuals to test the proportionality of subdistribution hazards for the Fine-Gray model, similar to the tests proposed by Grambsch and Therneau for independently censored data. We develop a score test for the time-varying coefficients based on the modified Schoen...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.5815
更新日期:2013-09-30 00:00:00
abstract::The semi-Markov assumption emphasizes the importance of time spent in a state. In order to compute this type of multistate model, most transition times are always considered to be exactly identified or right censored. However, in the longitudinal analysis of chronic diseases, investigators are often confronted with in...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.3100
更新日期:2007-12-30 00:00:00
abstract::In this article we develop flexible regression models in two respects to evaluate the influence of the covariate variables on the mixed Poisson and continuous responses and to evaluate how the correlation between Poisson response and continuous response changes over time. A scenario for dealing with regression models ...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.2776
更新日期:2007-09-10 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::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::Various R(2) statistics have been proposed for logistic regression to quantify the extent to which the binary response can be predicted by a given logistic regression model and covariates. We study the asymptotic properties of three popular variance-based R(2) statistics. We find that two variance-based R(2) statistic...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.2300
更新日期:2006-04-30 00:00:00
abstract::In the recent years, studies of hepatitis B (HBV) and hepatitis C virus (HCV) dynamics have drawn great attention as they provide insight into the process of virus elimination/production and of infected cells decay during antiviral treatment. Estimates of viral dynamic parameters may be used to determine the lifetime ...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.3457
更新日期:2008-12-30 00:00:00
abstract::This field study sought to measure the effects of dental delivery and school-based, dental health education on use of dental health care by children in grades K-6. We attempted to control for two potential confounding factors by an approximate randomization of children into treatment groups with stratification on grad...
journal_title:Statistics in medicine
pub_type: 临床试验,杂志文章,随机对照试验
doi:10.1002/sim.4780020107
更新日期:1983-01-01 00:00:00
abstract::The back-calculation method has been used to estimate the number of HIV infections from AIDS incidence data in a particular population. We present an extension of back calculation that provides estimates of the numbers of HIV infectives in different stages of infection. We model the staging process with a time-depende...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.4780110612
更新日期:1992-04-01 00:00:00
abstract::Multivariate outcomes measured longitudinally over time are common in medicine, public health, psychology and sociology. The typical (saturated) longitudinal multivariate regression model has a separate set of regression coefficients for each outcome. However, multivariate outcomes are often quite similar and many out...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.3589
更新日期:2009-06-15 00:00:00
abstract::Public health interventions are often designed to target communities defined either geographically (e.g. cities, counties) or socially (e.g. schools or workplaces). The group randomized trial (GRT) is regarded as the gold standard for evaluating these interventions. However, community leaders may object to randomizati...
journal_title:Statistics in medicine
pub_type: 杂志文章,随机对照试验
doi:10.1002/sim.4237
更新日期:2011-07-10 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::Interval-censored survival data often occur in medical studies, especially in clinical trials. In this case, many authors have considered estimation of a survival function. There is, however, relatively little discussion on estimating the variance of estimated survival functions. For right-censored data, a special cas...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.719
更新日期:2001-04-30 00:00:00
abstract::Many different methods have been proposed for the analysis of cluster randomized trials (CRTs) over the last 30 years. However, the evaluation of methods on overdispersed count data has been based mostly on the comparison of results using empiric data; i.e. when the true model parameters are not known. In this study, ...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.3681
更新日期:2009-10-30 00:00:00
abstract::Screening for a disease such as cancer is often regarded as a beneficial and successful strategy for reducing mortality. However, as with any clinical treatment or intervention, benefit cannot be assumed, and screening can entail both costs and harms, so the screening as a 'treatment' must undergo evaluation. An evalu...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.2037
更新日期:2005-02-28 00:00:00
abstract::The continual reassessment method (CRM) is an adaptive design for Phase I trials whose operating characteristics, including appropriate sample size, probability of correctly identifying the maximum tolerated dose, and the expected proportion of participants assigned to each dose, can only be determined via simulation....
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.8746
更新日期:2020-09-16 00:00:00
abstract::The one-step (Peto) method for obtaining pooled effect estimates can yield extremely biased results when applied to unbalanced data. Even for balanced studies, the one-step estimate may incorporate an unacceptable degree of bias. In place of the one-step estimate, we recommend use of ordinary Mantel-Haenszel, weighted...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.4780090307
更新日期:1990-03-01 00:00:00
abstract::We consider several sources of heterogeneity in a clinical trial with patients' survival time as the main response criterion: differences in prognosis which can be attributed to a latent or ignored prognostic factor; differences in treatment efficacy in subgroups of patients, and differences in treatment combinations ...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.4780060708
更新日期:1987-10-01 00:00:00
abstract::The receiver operating characteristic (ROC) curve is a popular technique with applications, for example, investigating an accuracy of a biomarker to delineate between disease and non-disease groups. A common measure of accuracy of a given diagnostic marker is the area under the ROC curve (AUC). In contrast with the AU...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.6863
更新日期:2016-06-15 00:00:00
abstract::The analysis of patient-reported outcomes or other psychological traits can be realized using the Rasch measurement model. When the objective of a study is to compare groups of individuals, it is important, before the study, to define a sample size such that the group comparison test will attain a given power. The Ras...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.6478
更新日期:2015-07-20 00:00:00
abstract::Increasing numbers of economic evaluations are conducted alongside randomised controlled trials. Such studies include factorial trials, which randomise patients to different levels of two or more factors and can therefore evaluate the effect of multiple treatments alone and in combination. Factorial trials can provide...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.7322
更新日期:2017-08-15 00:00:00
abstract::The 'at least as good as' criterion, introduced by Laster and Johnson for a continuous response variate, is developed here for applications with dichotomous data. This approach is adaptive in nature, as the margin of non-inferiority is not taken as a fixed difference; it varies as a function of the positive control re...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.2476
更新日期:2006-04-15 00:00:00