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利用多尺度最大似然检测混合分布AI 解读

A test of homogeneity tries to decide whether observations come from a single distribution or from a mixture of several distributions. A powerful theory has been developed for the case where the component distributions are members of an exponential family. When no parametric assumptions are appropriate, the standard approach is to test for bimodality, which is known not to be very sensitive for detecting heterogeneity. To develop a more sensitive procedure, this article…

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通过复变量模拟外推进行校正得分估计AI 解读

A Monte Carlo method of computing unbiased estimating equations for the analysis of data measured with error is described. Asymptotic distribution results are obtained for estimators derived from the Monte Carlo estimating equations. The method is illustrated with examples, applications, and simulation studies. The Monte Carlo estimating equations are corrected scores in the sense of Nakamura, and the proposed methods are closely related to the simulation method described by…

平稳类别时间序列的可变长度马尔可夫链筛自助法AI 解读

A bootstrap for stationary categorical time series based on the method of sieves is studied here. The data-generating process is approximated by the so-called variable-length Markov chain (VLMC), a flexible class of Markov models that allows for parsimonious structure. Then the resampling is given by simulating from the fitted model. It is shown that for a whole class of stationary categorical time series that is more general than VLMC, the VLMC sieve has faster rate of…

含非期望产出的多产出生产模型AI 解读

Many production processes yield both good outputs and undesirable ones (e.g., pollutants). In this article we develop a generalization of a stochastic frontier model that is appropriate for such technologies. We discuss efficiency analysis and, in particular, define technical and environmental efficiency in the context of our model. We develop methods for carrying out Bayesian inference and apply them to a panel data set of Dutch dairy farms, where excess nitrogen production…

潜变量层级模型中的经验贝叶斯与题目聚类效应AI 解读

Empirical Bayes regression procedures are often used in educational and psychological testing as extensions to latent variables models. The National Assessment of Educational Progress (NAEP) is an important national survey using such procedures. The NAEP applies empirical Bayes methods to models from item response theory to calibrate student responses to questions of varying difficulty. Due partially to the limited computing technology that existed when NAEP was first…

与表型相关的基因区域异质性非参数检验AI 解读

High-dimensional statistical problems arise in the investigation of the relationship between reduced sensitivity to antiretroviral drugs among human immunodeficiency virus-infected patients and viral genotypic patterns obtained from blood samples. This article develops a nonparametric approach for analyzing gene region heterogeneity associated with drug-resistance phenotype. The method is based on the distribution of distances between viral genetic sequences. The distance…

基于模型的聚类、判别分析与密度估计AI 解读

Cluster analysis is the automated search for groups of related observations in a dataset. Most clustering done in practice is based largely on heuristic but intuitively reasonable procedures, and most clustering methods available in commercial software are also of this type. However, there is little systematic guidance associated with these methods for solving important practical questions that arise in cluster analysis, such as how many clusters are there, which clustering…

时空数据的非可分平稳协方差函数AI 解读

Geostatistical approaches to spatiotemporal prediction in environmental science, climatology, meteorology, and related fields rely on appropriate covariance models. This article proposes general classes of nonseparable, stationary covariance functions for spatiotemporal random processes. The constructions are directly in the space–time domain and do not depend on closed-form Fourier inversions. The model parameters can be associated with the data's spatial and temporal…

回归插补下调查数据的样本相关系数AI 解读

Regression imputation is commonly used to compensate for item nonresponse when auxiliary data are available. It is common practice to compute survey estimators by treating imputed values as observed data and using the standard unbiased (or nearly unbiased) estimation formulas designed for the case of no nonresponse. Although the commonly used regression imputation method preserves unbiasedness for population marginal totals (i.e., survey estimators computed from imputed data…

利用辅助信息高效估计有限总体二次函数AI 解读

By viewing quadratic and other second-order finite population functions as totals or means over a derived synthetic finite population, we show that the recently proposed model calibration and pseudoempirical likelihood methods for effective use of auxiliary information from survey data can be readily extended to obtain efficient estimators of quadratic and other second-order finite population functions. In particular, estimation of a finite population variance, covariance,…

纵向边际模型中的非参数回归AI 解读

We consider nonparametric regression in a longitudinal marginal model of generalized estimating equation (GEE) type with a time-varying covariate in the situation where the number of observations per subject is finite and the number of subjects is large. In such models, the basic shape of the regression function is affected only by the covariate values and not otherwise by the ordering of the observations. Two methods of estimating the nonparametric function can be…

持照时长与延迟取证对交通事故风险的影响AI 解读

The driving history records of a sample of 13,794 Michigan public school students were followed for up to 13 years from their initial time-of-license to determine the separate effects of duration of licensure and delay of licensure on risk of crash. We propose a subject-specific lognormal accelerated failure time to model the expected time-to-crash as a function of age at time of licensure, duration of licensure, and a set of control covariates. When multiple time-to-crash…

疫苗保护效力随时间衰减的估计AI 解读

Whether the protection afforded by a vaccine wanes over time and if so, by how much, are important public health questions with implications for mass immunization programs. However, the measurement of such effects is fraught with difficulties. Generally, clinical trials are too short to provide evidence on waning effects. Thus it is necessary to rely on epidemiologic data, which are subject to ascertainment bias. Furthermore, standard epidemiologic measures, such as hazard…

可忽略性不确定下的小区域二元数据分层贝叶斯无响应模型AI 解读

In the National Crime Survey (NCS), data on victimization can be poststratified into domains determined by urbanization, type of place, and poverty level. There is much difficulty in the analysis of binary data with substantial nonresponse. We consider three Bayesian hierarchical models for binary nonresponse data, like those from the NCS, which are clustered within a number of domains or areas. As in small area estimation, one key feature is that each model “borrows…

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