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摘要暂缺

线性估计方程的刀切法：渐近理论与随机过程应用AI 解读

SUMMARY Let (X 1, X 2, ..., Xn) be a vector of (possibly dependent) random variables having distribution F(X, θ). Let θn be an estimating equation for θ, e.g. the score function or the maximum pseudolikelihood estimating equation in spatial processes. Let θn be the estimator obtained from G such that θn → θ0 in probability and n1/2(θn−θ0)→N(0,V) in distribution. In many situations, it is difficult to derive an analytical expression for V, e.g. for maximum pseudolikelihood…

临床神经解剖学中重复空间点模式的方差分析AI 解读

Our application concerns the analysis of the spatial distributions of pyramidal neurons in the cingulate cortex of human subjects in three diagnostic groupings. Our purpose is to develop and apply several methods for the analysis of replicated spatial point patterns to identify anatomical differences between normal, schizoaffective, and schizophrenic persons at the time of death. We begin with a scaled Poisson analysis that uncovers significant differences between the groups…

随机空间模式分形维数的极大似然估计AI 解读

Two approximate maximum likelihood estimates of the fractal dimension are suggested for random point patterns and planar curves, based on the distributions of the Palm probability and the spectrum.

家庭需求的空间模式AI 解读

This paper discusses economic processes that may give rise to spatial patterns in data and explores the relative merits of alternative modeling approaches when data are spatially correlated. An estimation scheme is presented that allows for spatial random effects and attention is focused on cases in which such a framework may be preferred to the more general fixed effects framework that nests it. The models presented are used together with information on the location of…

空间点过程的删失距离强度估计AI 解读

The use of censoring in conjunction with distance-based estimation of the intensity of a spatial point process is considered. Censoring, in this context, may be motivated by practical considerations such as reduction of sampling effort, but it may also be considered as a method for preventing the overlap of search regions and for eliminating edge effects. Maximum likelihood estimators that utilize censored point-plant measurements or censored T-square measurements are…

Numerical simulations recently reported in the literature have shown that the profile likelihood associated with the estimation of covariance range parameters for a Gaussian field can be multimodal. Here we complement these recent results by considering covari-ances with unknown nugget, scale and range parameters. Estimation is performed in a restricted maximum likelihood framework. For unbounded sampling domains and known range parameter, conditions ensuring asymptotic…

Two approximate maximum likelihood estimates of the fractal dimension are suggested for random point patterns and planar curves, based on the distributions of the Palm probability and the spectrum.

基于删失距离的空间点过程强度估计AI 解读

The use of censoring in conjunction with distance-based estimation of the intensity of a spatial point process is considered. Censoring, in this context, may be motivated by practical considerations such as reduction of sampling effort, but it may also be considered as a method for preventing the overlap of search regions and for eliminating edge effects. Maximum likelihood estimators that utilize censored point-plant measurements or censored T-square measurements are…

酸沉降估计的对数正态方法与移动窗口方法AI 解读

The deposition of heightened levels of sulfuric and nitric acid through rainfall in the United States may adversely affect the environment. For example, soils may become toxic to native tree species because of soil acidification. Ecological effects models being built to study these potential problems have a need for regional deposition estimates with associated measures of uncertainty. However, statistical estimation of the deposition process is complicated by a strong…

非均匀人口中的空间聚集检测AI 解读

SUMMARY A new method for detecting spatial clustering of events in populations with non-uniform density is proposed. The method is based on selecting controls from the population at risk and computing interpoint distances for the combined sample. Nonparametric tests are developed which are based on the number of cases among the k nearest neighbours of each case and the number of cases nearer than the k nearest control. The performance of these tests is evaluated analytically…

摘要暂缺

有序类别列联表的精确推断AI 解读

This article proposes an efficient numerical algorithm for small-sample exact inferences in contingency tables having ordinal classifications. The inferences, which apply conditional on the observed marginal totals, also provide an exact analysis for the log-linear model of linear-by-linear association for cell probabilities. An exact test of independence has a one-sided P value equal to the null probability that model-based maximum likelihood estimates of odds ratios are at…

多朋友选择中的同质性与社会距离：条件对称对数双线性关联模型AI 解读

This article presents an analysis of friendship choice data by focusing on homophily (or inbreeding bias) and social distance revealed in the patterns of both association between subjects' and friends' statuses and association among friends' statuses. These two aspects of inbreeding bias and social distance are simultaneously taken into account in modeling the data of friendship choice from subjects with different numbers of friends. The statuses of friends are expressed in…

社会网络的伪似然估计AI 解读

Interest in log-linear modeling for social-network data has grown steadily since Holland and Leinhardt (1981) proposed their p 1 model. That model was designed for a single binary relationship (directed graph) representing interactions between individuals. It assumed that interactions between pairs of individuals are mutually independent. Subsequent work has extended the model in various ways, including block-modeling and the case of dependence between pairs of individuals.…

单隐层前馈网络学习的若干渐近结果AI 解读

We investigate the properties of a recursive estimation procedure (the method of “back-propagation”) for a class of nonlinear regression models (single hidden-layer feedforward network models) recently developed by cognitive scientists. The results follow from more general results for a class of recursive m estimators, obtained using theorems of Ljung (1977) and Walk (1977) for the method of stochastic approximation. Conditions are given ensuring that the back-propagation…

空间点过程二阶强度加权积分的估计AI 解读

SUMMARY This paper considers the nonparametric estimation of the integral J=∫0Ttλ2(t)φ(t)dt where λ2(t) is the unknown second-order intensity function of a two-dimensional stationary isotropic point process observed in some region and φ(t) is known for t ϵ [0, T]. An unbiased estimator of J is derived, and a computationally fast approximation to it is proposed. The estimator is then used to obtain a kernel method for smoothing point process data, a new estimator of the…

稳定美国癌症死亡率地图的经验贝叶斯方法AI 解读

"The geographic mapping of age-standardized, cause-specific death rates is a powerful tool for identifying possible etiologic factors, because the spatial distribution of mortality risks can be examined for correlations with the spatial distribution of disease-specific risk factors. This article presents a two-stage empirical Bayes procedure for calculating age-standardized cancer death rates, for use in mapping, which are adjusted for the stochasticity of rates in small…

摘要暂缺

田间小区试验中 Papadakis 及其他非线性处理对比估计量的无偏性AI 解读

Spatial methods for the analysis of field-plot experiments are considered. Estimators of treatment contrasts obtained by these methods are generally complicated nonlinear functions of the observations. Sufficient conditions for these estimators to be unbiased under a postulated true model are obtained.

空间线性模型中似然的多峰性AI 解读

A popular covariance scheme used for the spatial linear model in geostatistics has spherical form. However, the likelihood is not twice differentiable with respect to the range parameter, and this raises some questions regarding the unimodality of the likelihood. We compare the likelihoods of the spatial linear model for small samples under this scheme and the doubly geometric scheme. Also, a power covariance with range parameter is proposed. In view of potential multimodal…

田间小区实验中 Papadakis 及其他非线性处理对比估计量的无偏性AI 解读

Spatial methods for the analysis of field-plot experiments are considered. Estimators of treatment contrasts obtained by these methods are generally complicated nonlinear functions of the observations. Sufficient conditions for these estimators to be unbiased under a postulated true model are obtained.

判定时间序列非平稳性的图形方法AI 解读

Integrated processes as models for time series data have proved to be an important component of the highly flexible class of ARIMA(p, d, q) models. Determining the amount of differencing, d, has been a difficult task: too little and the process is not yet second-order stationary; too much and the process is more variable than it need be. It is shown that by introducing the notion of generalized covariances, developed by Matheron (1973) for spatial processes, the amount of…

用于估计置换推断精确概率的重要性抽样AI 解读

This article discusses importance sampling as an alternative to conventional Monte Carlo sampling for estimating exact significance levels in a broad class of two-sample tests, including all of the linear rank tests (with or without censoring), homogeneity tests based on the chi-squared, hypergeometric, and likelihood ratio statistics, the Mantel—Haenszel trend test, and Zelen's test for a common odds ratio in several 2 × 2 contingency tables. Inference is based on randomly…