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迭代定义统计量的影响函数AI 解读

SUMMARY Hampel's influence function and its finite-sample counterparts are the basis for a number of diagnostic statistics. These diagnostics can be expensive to compute in the natural way when the estimation calculations are iterative, as they frequently are when maximum likelihood or robust methods are used. We show how the influence function can be calculated in these situations by implicit differentiation of the fixed-point equation satisfied by the limit of the…

因果型空间自回归过程估计量的偏差AI 解读

We study the asymptotic distribution of Yule-Walker and least squares estimators for twodimensional causal autoregressive processes observed on a rectangular part of a lattice. An explicit expression for the asymptotic bias of Yule-Walker estimators is obtained. It is shown that this bias disappears if we use the so-called unbiased sample autocovariance function or least squares estimators.

病例对照研究中 Logistic 回归的稳健估计AI 解读

Consider a logistic regression model under case-control sampling. Prentice & Pyke (1979) showed that the logistic slope estimates with case-control sampling may be estimated from a standard prospective logistic regression program and that the resulting standard errors are asymptotically correct. Since logistic regression estimates are nonrobust, we propose and analyze robust estimates of the slope parameters. We focus specifically on estimates which downweight observations…

基于标记过程的一致预测规则框架AI 解读

Recently interest has developed regarding the statistical properties and uses of marker processes in the context of the analysis of failure time data or survival analysis. A marker process is a stochastic process that acts as a time dependent covariate that is internal to the unit under study in the language of Kalbfleisch & Prentice (1980). As such the sample path of the process up to a certain point in time may carry information about the subsequent hazard for failure.…

纵向二元响应的似然分析方法AI 解读

In this paper, we discuss a likelihood-based method for analysing correlated binary responses based on a multivariate model. It is related to the pseudo-maximum likelihood approach suggested recently by Zhao & Prentice (1990). Their parameterization results in a simple pairwise model, in which the association between responses is modelled in terms of correlations, while the present paper uses conditional log odds-ratios. With this approach, higher-order associations can be…

非线性回归中的杠杆、局部影响与曲率AI 解读

The connections between measures of leverage, statistical curvature, and the local influence of a mean-shift perturbation are explored in nonlinear regression models. The circumstances under which the Jacobian leverage reduces to a commonly-used linear approximation are found to be connected to the effective residual curvature of the nonlinear model. The local influence of a mean-shift perturbation in the model function is seen to be closely related to the Jacobian leverage.

Cusum、von Neumann 与平滑型拟合优度检验的共同结构AI 解读

Recent papers by Munson & Jernigan (1989) and Buckley (1991) propose nonparametric tests for the hypothesis of no predictor effect in regression. The Munson-Jernigan test is similar to the von Neumann (1941) test, while that of Buckley is based on a functional of cusums. These tests are shown to be special cases of a wider class of tests based on nonparametric function estimation ideas. Fourier analysis is used to qualitatively compare the Munson & Jernigan and Buckley tests…

从置信区间进行贝叶斯与似然计算AI 解读

Recently there has been considerable progress on setting good approximate confidence intervals for a single parameter θ in a multi-parameter family. Here we use these frequentist results as a convenient device for making Bayes, empirical Bayes and likelihood inferences about θ. A simple formula is given that produces an approximate likelihood function Lx†(θ) for θ, with all nuisance parameters eliminated, based on any system of approximate confidence intervals. The…

暂时性均值变化备择下的变点检验AI 解读

The purpose of this paper is to discuss the tests to detect an epidemic alternative in the mean value of a sequence of independent normal variables. Various test statistics, such as the likelihood ratio, the score-like statistic, Levin & Kline's statistic, the semilikelihood ratio, and the recursive residual, are studied. The large deviation approximations to the significance levels and powers are developed by integrating approximations to conditional boundary crossing…

多中心临床试验的二元数据分析AI 解读

We develop several methods for estimating the treatment effect difference defined as the overall log-odds ratio of favourable response in a multicentre clinical trial comparing two treatments with binary response. A simulation study compares the bias and mean squared error of the point estimates and the exact coverage probabilities of confidence intervals obtained distributions.

摘要暂缺

结合先验信息的非参数样条回归AI 解读

By using prior information about the regression curve we propose new nonparametric regression estimates. We incorporate two types of information. First, we suppose that the regression curve is similar in shape to a family of parametric curves characterized as the solution to a linear differential equation. The regression curve is estimated by penalized least squares with the differential operator defining the smoothness penalty. We discuss in particular growth and decay…

改善贝叶斯推断参数化的诊断图AI 解读

A major problem with the Bayesian analysis of statistical models is that the computation of posterior and predictive summaries typically requires the numerical evaluation of complicated multivariate integrals. The accuracy and efficiency of these computations are usually sensitive to the choice of parameterization for the statistical model. This paper describes a graphical method which can be used both for assessing a proposed parameterization and choosing a new improved…

二阶自回归多项式根的大样本分布AI 解读

The roots of the characteristic polynomial of an autoregressive process are sometimes of interest. In this paper, we show that the estimated roots of a second order autoregressive polynomial have different asymptotic distributions depending upon whether the true roots are equal or unequal.

含测量误差的 probit 回归似然分析AI 解读

Likelihood analysis is proposed for a probit regression model when one of the explanatory variables is measured with error and replicate measurements of that variable are available on some of the subjects. The distribution of the measurement error and of the unknown explanatory variable, conditional on the known variables, are both taken to be normal. The maximum likelihood estimates can be computed exactly with the EM algorithm. Likelihood ratio tests and confidence…

Box–Cox 幂变换模型的敏感性分析：对比参数AI 解读

Sensitivity analysis is an important tool for the evaluation of scientific models. We consider the Box-Cox power transformation model and study the sensitivity for the estimated slope vector when the transformation parameter is perturbed. This is a key issue in the debate among Bickel & Doksum (1981), Box & Cox (1982) and Hinkley & Runger (1984) on the application of the power transformation model. Hinkley & Runger (1984) conjectured that Box & Cox's (1964) z transformation…

基于相干系统累积发生函数的两样本检验AI 解读

Suppose that n1 and n2 independent copies of a coherent system composed of m components operate in two different environments. All copies are monitored until their failure. The data consist of the lifetimes of all the components which fail before the system and the time to failure of the system which also is the censoring time for the components not yet failed. In this paper we propose a class of tests based on the incidence functions of the component failures obtained from…

von Mises–Fisher 分布方向参数的中位数型估计AI 解读

We study three median-type estimators of direction: the normalized spatial median, L1-estimator on the sphere and spherical median. Their asymptotic distributions, efficiencies, influence functions and sensitivities are given at the von Mises-Fisher model. A simulation study is also carried out to compare their finite sample performance in terms of mean squared errors. We conclude that overall the normalized spatial median is the preferred estimator.

含确定性趋势的自回归积分移动平均模型中的若干单位根检验AI 解读

For a nonstationary time series we consider a model which can accommodate the possibility of deterministic and stochastic trends. Assuming that we are primarily interested in testing for the stochastic trend, that is, for a unit root in the time series, we employ the Lagrange multiplier principle and obtain test statistics. The asymptotic distributions of the test statistics. The asymptotic distributions of the test statistics are characterized by functionals of stochastic…

基于矩的生物等效性判定准则AI 解读

In comparative bioavailability trials, the focus in the determination of bioequivalence has been to show that the average bioavailability on a test formulation is similar to the average bioavailability on a reference formulation. It has been argued that this is not adequate to insure interchangeability of formulations. We introduce a moment-based criterion which ensures interchangeability for at least a certain proportion of the population. An algorithm is given for…

利用替代失效时间数据提高临床试验的成本效益AI 解读

In clinical trials with failure time, outcomes, the cost of follow-up for the endpoint of primary interest is sometimes expensive. In many of these settings, one or more secondary or surrogate failure time outcomes are also available which either occur much earlier or are much less expensive to follow than the primary outcome. This paper presents a method for using these secondary outcomes to increase the power of detecting a treatment effect on the primary outcome only,…

通过广义线性回归拟合长记忆模型AI 解读

There is an increasing awareness of the importance of long-memory models in statistical applications. If long memory is present, it has to be taken into account in order to obtain reliable tests and confidence intervals. One obstacle to using models with long memory in routine statistical analysis has been the lack of easily available and sufficiently versatile statistical software. Here we propose a simple but flexible class of parametric models, which can be used to model…

摘要暂缺

拟似然方法中的偏差函数AI 解读

We introduce a deviance function that can be used in conjunction with the quasi-likelihood method. The need for such functions arises when the quasi-log likelihood function is not uniquely defined. The deviance is obtained by projecting a pair of centred likelihood ratios onto the direct sum of two Hilbert spaces spanned by the observations. Locally at the null and the alternative hypotheses, the deviance function is equivalent to the quasi-log likelihood ratio provided that…