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具有随机化后响应指标的临床试验半参数两样本检验AI 解读

In many clinical trials involving survival endpoints, one has additional data on some binary indicator of ‘response’, such as initial tumour shrinkage in cancer trials. This paper studies the case of randomised clinical trials where the response indicator is available shortly after randomisation, and where one can assume that, within each stratum defined by the response indicator, a two treatment-group proportional-hazards model holds. The same model may also describe some…

Logistic 回归的层级贝叶斯半参数方法AI 解读

A simple procedure is proposed for exact computation to smooth Bayesian estimates for logistic regression functions, when these are not constrained to lie on a fitted regression surface. Exact finite sample inferences and predictions are available, together with an exact residual analysis. The prior distribution relates to O'Hagan's assumptions for a normal regression function. A global shrinkage parameter and local smoothness parameter can be evaluated from the current data…

截断数据的半参数似然比推断AI 解读

In astronomic, demographic, epidemiologic, and other studies, the variable of interest, say the survival time, is often truncated by an associated variable. In many situations, the distribution of the truncation variable can be described by a parametric form. Unlike in the standard right-censorship model in which the censoring distribution is noninformative, knowledge of the truncation distribution can be used to improve estimation of the survival distribution. This article…

半参数变换模型下的生存概率预测AI 解读

Prediction of survival probabilities for future patients is one of the main goals of fitting survival data with regression models. In this article we consider a large class of semiparametric transformation models, which includes the well-known proportional hazards and proportional odds models, for the analysis of failure time data. Specifically, we propose pointwise and simultaneous confidence interval procedures for the survival probability of future patients with specific…

半参数单指标建模与固定连接函数建模的比较AI 解读

Discrete choice models are frequently used in statistical and econometric practice. Standard models such as logit models are based on exact knowledge of the form of the link and linear index function. Semiparametric models avoid possible misspecification but often introduce a computational burden especially when optimization over nonparametric and parametric components are to be done iteratively. It is therefore interesting to decide between approaches. Here we propose a…

部分线性模型中的半参数推断AI 解读

In a partial linear model, the dependence of a response variate Y on covariates (W, X$ is given by $$Y = W \beta + \eta(X) + \mathscr{E}$$ where $\mathscr{E}$ is independent of $(W, X)$ with densities g and f, respectively. In this paper an asymptotically efficient estimator of $\beta$ is constructed solely under mild smoothness assumptions on the unknown $\eta$, f and g, thereby removing the assumption of finite residual variance on which all least-squares-type estimators…

若干指数型面板模型有效半参数估计的一则注记AI 解读

This paper investigates the semiparametric efficiency of the conditional maximum likelihood estimation in some panel models. The nonparametric component of the model is the unknown distribution of the fixed effect. For the exponential panel model, there exists a complete sufficient statistic for the fixed effect. When the complete sufficient statistic does not depend on the parameter of interest, the conditional maximum likelihood estimator (CMLE) achieves the semiparametric…

含稳定过程的矩阵随机积分弱收敛AI 解读

This paper generalizes the univariate results of Chan and Tran (1989, Econometric Theory 5, 354–362) and Phillips (1990, Econometric Theory 6, 44–62) to multivariate time series. We develop the limit theory for the least-squares estimate of a VAR(l) for a random walk with independent and identically distributed errors and for I(1) processes with weakly dependent errors whose distributions are in the domain of attraction of a stable law. The limit laws are represented by…

离散选择模型中位置及其他矩的半参数估计AI 解读

Latent variable discrete choice model estimation and interpretation depend on the density function of the latent variable's unobserved random component. This paper provides a simple semiparametric estimator of the moments of this density. The results can be used as starting values for parametric estimators, to estimate the appropriate location and scaling for semiparametric estimators, for specification testing including tests of latent error skewness and kurtosis, and to…

含非参数生成解释变量的单指标模型半参数估计AI 解读

This paper develops a theory of estimating parameters of a generated regressor model in which some explanatory variables in the equation of interest are the unknown conditional means of certain observable variables given other observable regressors. The paper imposes a weak nonparametric restriction on the form of the conditional means and maintains a single-index assumption on the distribution of the dependent variable in the equation of interest. The estimation method…

加权平均生存检验统计量：删失生存数据的一类距离检验AI 解读

Summary A class of test statistics is introduced which is sensitive against the alternative of stochastic ordering in the two-sample censored data problem. The test statistics for evaluating a cumulative weighted difference in survival distributions are developed while taking into account the imbalances in base-line covariates between two groups. This procedure can be used to test the null hypothesis of no treatment effect, especially when base-line hazards cross and…

混合谱时间序列的半参数贝叶斯推断AI 解读

Summary A Bayesian analysis is presented of a time series which is the sum of a stationary component with a smooth spectral density and a deterministic component consisting of a linear combination of a trend and periodic terms. The periodic terms may have known or unknown frequencies. The advantage of our approach is that different features of the data—such as the regression parameters, the spectral density, unknown frequencies and missing observations—are combined in a…

基于相关随机效应模型的同质性广义得分检验AI 解读

Summary We present a family of tests based on correlated random effects models which provides a synthesis and a generalization of recent work on homogeneity testing. In these models each subject has a particular random effect, but the random effects between subjects are correlated. We derive the general form of the score statistic for testing that the random effects have a variance equal to 0. We apply this result to both parametric and semi-parametric models. In both cases…

不同等待时间概念下的 Cox 回归：1853 年新奥尔良黄热病疫情AI 解读

Event data can often be analysed using different concepts of waiting time. Our application offers three choices: calendar-time, age, and duration of residence in New Orleans. We exploit the semi-parametric features of Cox regression and estimate parallel specifications in which mortality risk is treated as an arbitrary function of one of the three alternative time measures, while the remaining two enter the hazard parametrically. Comparisons of the parameter estimates with…

不同等待时间概念下的Cox回归：1853年新奥尔良黄热病疫情AI 解读

Event data can often be analysed using different concepts of waiting time. Our application offers three choices: calendar-time, age, and duration of residence in New Orleans. We exploit the semi-parametric features of Cox regression and estimate parallel specifications in which mortality risk is treated as an arbitrary function of one of the three alternative time measures, while the remaining two enter the hazard parametrically. Comparisons of the parameter estimates with…

双侧删失数据的线性回归AI 解读

Linear regression with doubly censored responses is considered. Buckley-James-Ritov-type estimators are proposed. Semiparametric information and projective scores are discussed. An expansion of the estimating equations is obtained under fairly general assumptions. Sufficient conditions are given for the asymptotic consistency and normality of the estimators.

删失数据两样本位置—尺度模型的经验过程方法AI 解读

To compare two samples of possibly right-censored failure times, a location-scale model, without assuming the distribution form, is considered for the log-transformed data. This new accelerated failure time model is introduced to accommodate the possible heterogeneity between within-treatment variations of the two groups considered. One distinct feature of this model is that, with the presence of heterogeneity, statistical inferences on both location and scale parameters…

含离散协变量单指标模型的直接半参数估计AI 解读

Others have developed average derivative estimators of the parameter β in the model E(Y|X = x) = G(xβ), where G is an unknown function and X is a random vector. These estimators are noniterative and easy to compute but require that X be continuously distributed. This article develops a noniterative, easily computed estimator of β for models in which some components of X are discrete. The estimator is n ½ consistent and asymptotically normal. An application to data on product…

估计通常每日摄入量分布的半参数变换方法AI 解读

The distribution of usual intakes of dietary components is important to individuals formulating food policy and to persons designing nutrition education programs. The usual intake of a dietary component for a person is the long-run average of daily intakes of that component for that person. Because it is impossible to directly observe usual intake for an individual, it is necessary to develop an estimator of the distribution of usual intakes based on a sample of individuals…

ARCH 模型的条件分位数估计与推断AI 解读

Quantile regression methods are suggested for a class of ARCH models. Because conditional quantiles are readily interpretable in semiparametric ARCH models and are inherendy easier to estimate robustly than population moments, they offer some advantages over more familiar methods based on Gaussian likelihoods. Related inference methods, including the construction of prediction intervals, are also briefly discussed.

特征价格函数的半参数估计AI 解读

Previous work on the preferred specification of hedonic price models usually recommended a Box-Cox model. In this paper we note that any parametric model involves implicit restrictions and they can be reduced by using a semiparametric model. We estimate a benchmark parametric model which passes several common specification tests, before showing that a semiparametric model outperforms it significantly. In addition to estimating the model, we compare the predictions of the…

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彩池博彩市场中预期假说的半参数（分布无关）检验AI 解读

The expectations hypothesis maintains that a current forward or futures price should be an unbiased forecast of the expected future price. This paper tests the expectations hypothesis in the parimutuel gambling market for greyhound racing parametric and semiparametric estimators. Parimutuel gambling markets are similar to speculative asset markets in many regards. Conventional maximum likelihood tests of asset pricing require a priori specification of the statistical…

休闲出游次数模型中的过多零值AI 解读

This article develops a modeling approach for a count data set for recreational boating trips that shows a frequency of zero counts significantly higher than that expected for Poisson distributed data. As alternatives to the Poisson regression, the authors consider several parametric and semiparametric mixed and modified Poisson models. The analysis suggests that the negative binomial hurdles model, which allows for overdispersion and also accommodates the presence of…