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利用前瞻性数据估计HIV母婴传播率与儿童艾滋病潜伏期AI 解读

This article considers the estimation of the rate of vertical human immunodeficiency virus (HIV) transmission and the pediatric acquired immune deficiency syndrome (AIDS) incubation period using data from birth cohort studies. Standard methods of analysis, which ignore children whose infection status is not established, may lead to biased estimates. Methods based on modeling the disappearance of HIV antibody or appearance of virus are inefficient, as they essentially rely on…

二元结局与有序依从性安慰剂对照试验的因果推断AI 解读

We propose a likelihood-based method to analyze the causal effect of partial compliance (i.e., unplanned partial exposure to treatment or placebo) in the LRC-CPPT data, a prevention trial with long term follow-up previously analyzed by Efron and Feldman. Initially, we construct ordered compliance categories and dichotomize response. Assuming increased exposure to cholestyramine does not increase cholesterol, we estimate exposure—response curves in different compliance…

利用前瞻性数据估计HIV母婴传播率与儿童艾滋病潜伏期AI 解读

This article considers the estimation of the rate of vertical human immunodeficiency virus (HIV) transmission and the pediatric acquired immune deficiency syndrome (AIDS) incubation period using data from birth cohort studies. Standard methods of analysis, which ignore children whose infection status is not established, may lead to biased estimates. Methods based on modeling the disappearance of HIV antibody or appearance of virus are inefficient, as they essentially rely on…

二元结局与有序依从性的安慰剂对照临床试验因果推断AI 解读

We propose a likelihood-based method to analyze the causal effect of partial compliance (i.e., unplanned partial exposure to treatment or placebo) in the LRC-CPPT data, a prevention trial with long term follow-up previously analyzed by Efron and Feldman. Initially, we construct ordered compliance categories and dichotomize response. Assuming increased exposure to cholestyramine does not increase cholesterol, we estimate exposure—response curves in different compliance…

工会对工资结构的影响：纵向分析AI 解读

This paper studies the effects of unions on the structure of wages using an estimation technique that accounts for misclassification errors in reported union status and potential correlations between union status and unobserved productivity. The model is estimated separately for five skill groups using a panel data set formed from the U.S. Current Population Survey. The results suggest that unions raise wages more for workers with lower levels of observed skills. Union…

依赖删失下两个失效时间分布的比较AI 解读

In a randomised clinical trial to compare two groups of patients, suppose that the time to disease occurrence, the major response variable, may be subject to dependent censoring by death or selective patient withdrawal, while the patients who have reached the disease endpoint are followed for their secondary endpoints or survival information. To adjust for the dependent censoring in assessing the group difference in disease occurrence, we assume that, on a logarithmic scale,…

随机区组设计的半参数贝叶斯模型AI 解读

A model is proposed for a Bayesian semiparametric analysis of randomised block experiments. The model is a hierarchical model in which a Dirichlet process is inserted at the middle stage for the distribution of the block effects. This model allows an arbitrary distribution of block effects, and it results in effective estimates of treatment contrasts, block effects and the distribution of block effects. An effective computational strategy is presented for describing the…

使用工具变量识别因果效应AI 解读

We outline a framework for causal inference in settings where assignment to a binary treatment is ignorable, but compliance with the assignment is not perfect so that the receipt of treatment is nonignorable. To address the problems associated with comparing subjects by the ignorable assignment—an “intention-to-treat analysis”—we make use of instrumental variables, which have long been used by economists in the context of regression models with constant treatment effects. We…

利用工具变量识别因果效应：评论AI 解读

We outline a framework for causal inference in settings where assignment to a binary treatment is ignorable, but compliance with the assignment is not perfect so that the receipt of treatment is nonignorable. To address the problems associated with comparing subjects by the ignorable assignment-an intention-to-treat analysis-we make use of instrumental variables, which have long been used by economists in the context of regression models with constant treatment effects. We…

连续稀释试验重复二元数据的非参数混合效应模型：艾滋病病毒负荷估计AI 解读

This article develops methods for estimating treatment effects in mixed-effects models using outcome data gathered from serial dilution assays. Our application allows us to estimate the viral burden of HIV infection before and after antiviral treatment from cell dilution assays. This assay is designed to determine the infectious units per patient peripheral blood mononuclear cell (PBMC). The infectious unit is the amount of virus required to produce detectable HIV infection…

摘要暂缺

连续稀释试验重复二元数据的非参数混合效应模型：艾滋病病毒负荷估计AI 解读

This article develops methods for estimating treatment effects in mixed-effects models using outcome data gathered from serial dilution assays. Our application allows us to estimate the viral burden of HIV infection before and after antiviral treatment from cell dilution assays. This assay is designed to determine the infectious units per patient peripheral blood mononuclear cell (PBMC). The infectious unit is the amount of virus required to produce detectable HIV infection…

离散与连续重复测量中随机化后协变量的处理AI 解读

SUMMARY Adjusting for covariates observed post randomization is a difficult issue in randomized clinical trials. One approach is to enter these covariates as time-dependent covariates in a general linear model. However, this approach fails to account for interactions between the primary end point and confounding variable as they evolve over time. In this paper, we adopt the view that, since the confounder is observed following randomization, it should be treated as an…

多项数据的推断：从一袋弹珠中学习AI 解读

SUMMARY A new method is proposed for making inferences from multinomial data in cases where there is no prior information. A paradigm is the problem of predicting the colour of the next marble to be drawn from a bag whose contents are (initially) completely unknown. In such problems we may be unable to formulate a sample space because we do not know what outcomes are possible. This suggests an invariance principle: inferences based on observations should not depend on the…

持续期模型中的样本选择与初始条件：来自培训实验的证据AI 解读

The authors investigate the separate effects of a training program on the duration of participants' subsequent employment and unemployment spells. This program randomly assigned volunteers to treatment and control groups. However, the treatments and controls experiencing subsequent employment and unemployment spells are not generally comparable subsets of the initial groups. Standard practice in duration models ignores this issue, leading to a sample selection problem and…

非随机样本与观察性研究中的分位数AI 解读

In a nonrandom sample or a nonrandomized comparison of treated and control groups, methods are developed for displaying the sensitivity of confidence intervals for population quantiles to the magnitude of the departure from random selection. Quantiles of a single distribution and for a shift in two distributions are both discussed. These confidence intervals are based on a new inequality for the distribution of the number of successes in a nonrandom sample or nonrandomized…

非随机样本与观察性研究中的分位数AI 解读

In a nonrandom sample or a nonrandomized comparison of treated and control groups, methods are developed for displaying the sensitivity of confidence intervals for population quantiles to the magnitude of the departure from random selection. Quantiles of a single distribution and for a shift in two distributions are both discussed. These confidence intervals are based on a new inequality for the distribution of the number of successes in a nonrandom sample or nonrandomized…

存在依赖删失时的半参数回归估计AI 解读

We propose a semiparametric estimation procedure for estimating the regression of an outcome Y, measured at the end of a fixed follow-up period, on baseline explanatory variables X, measured prior to start of follow-up, in the presence of dependent censoring given X. The proposed estimators are consistent when the data are ‘missing at random’ but not ‘missing completely at random’ (Rubin, 1976), and do not require full specification of the complete data likelihood.…

异质处理效应下半参数两样本模型的经验过程方法AI 解读

SUMMARY Two types of semiparametric model are proposed for comparing two samples with possibly heterogeneous treatment effects. One model is a two-sample location-scale model which assumes that the Q-Q-plot of the two distributions involved is linear; the other is the class of two-sample transformation models which assume parametric forms for a probability plot—the receiver operating characteristic curve. The empirical process approach is used to construct strong…

比例风险回归中的模型误设AI 解读

The proportional hazards model is frequently used to evaluate the effect of treatment on failure time events in randomised clinical trials. Concomitant variables are usually available and may be considered for use in the primary analyses under the assumption that incorporating them may reduce bias or improve efficiency. In this paper we consider two approaches to including covariate information: regression modelling and stratification. We focus on the setting where covariate…

不完整数据下的有序备择检验AI 解读

In testing the null hypothesis of no treatment effects in a randomized block experiment, a researcher may restrict attention to an ordered alternative and thereby increase the power of his test. Jonckheere and later Page proposed such test statistics based on the Kendall and Spearman correlation coefficients. Motivated by notions of distance between permutations, we generalize Jonckheere's and Page's tests to the situation in which one or more observations are missing from…

不完整数据下有序备择假设的检验AI 解读

In testing the null hypothesis of no treatment effects in a randomized block experiment, a researcher may restrict attention to an ordered alternative and thereby increase the power of his test. Jonckheere and later Page proposed such test statistics based on the Kendall and Spearman correlation coefficients. Motivated by notions of distance between permutations, we generalize Jonckheere's and Page's tests to the situation in which one or more observations are missing from…

关于遗漏混杂因素所致偏差的札记AI 解读

In observational studies some confounders may be unknown and therefore omitted from the analysis while others are adjusted for. Approximations to the functions defining the relationship between the parameters in the full and reduced models are proposed leading to asymptotic bias estimates. Numerical calculations for logistic and Poisson regression models show good agreement between asymptotic and simulation bias. A data set containing the relationship between low birth…

可变处理强度模型中平均因果效应的两阶段最小二乘估计AI 解读

Two-stage least squares (TSLS) is widely used in econometrics to estimate parameters in systems of linear simultaneous equations and to solve problems of omitted-variables bias in single-equation estimation. We show here that TSLS can also be used to estimate the average causal effect of variable treatments such as drug dosage, hours of exam preparation, cigarette smoking, and years of schooling. The average causal effect in which we are interested is a conditional…