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851.
“情感过滤”和“输入”是影响外语习得的两大重要因素。该文首先论述了“情感过滤”对外语习得和学习的作用机制 ,然后分析了引起“情感过滤”的四大情感因素 ,并提出怎样减少或消除学习者的“情感过滤”来提高英语教学质量的方法。  相似文献   
852.
Formulae are given for the Fisher information loss on parameters for the mean and the variance when some values of a Gaussian process are not observed. The special case of a one-parameter first-order conditional process on a rectangular lattice is considered in detail, and formulae are compared with numerical results.  相似文献   
853.
Since departures from the classical assumptions regarding the disturbances in a linear tegression model arise frequently in empirical application, deveral computationally Straightforward procedutes are presented in this paper for testiog non-nested models when the disturbances of these models follow first- or higher-order autoregressive processes. Anempirical example is used to illustrate how the procedures may be used to test competing Keynesian and New Classical non-nested models of unemployment for the U.S using annual time series data for 1955-85.  相似文献   
854.
This study advances understanding of environmental inequality by examining its production through the interaction of two ubiquitous and ongoing urban-ecological processes: industrial land-use changes and changing patterns of residential segregation. We employ longitudinal data from the Rhode Island Directory of Manufacturers (1953–2012) and tract-level US Census data measured at four panel-years (1980, 1990, 2000, and 2010) to study the effects of these interactions in Rhode Island’s historical industrial cities of Providence, Pawtucket, and Central Falls. Spatial patterning analysis and hybrid spatial panel modeling of residential exposure to active and legacy industrial sites in relation to ongoing racial and industrial change reveal two novel findings. First, we find a “legacy effect,” suggesting that the spatial organization of industrial activities prior to the study period has measurable impacts on patterns of residential segregation in later decades. Our results also indicate that over the study period Latinx and African-American residents have become increasingly less likely to bear disproportionate impacts of active manufacturing sites, despite very different spatial patterns of population growth. This is strong evidence that environmental inequality formation is a variable process in which historically distinct pathways can lead to similarly disproportionate exposure to environmental risk.  相似文献   
855.
856.
本文对改进模糊相似选择方法作出了进一步的改进,综合权重和海明距离两方面因素,对事物按优劣程度排序,从而更加准确有效,符合实际。  相似文献   
857.
利用Banach不动点定理讨论一类带有初值条件的n阶迭代泛函微分方程解的存在性和唯一性.  相似文献   
858.
Missing observations due to non‐response are commonly encountered in data collected from sample surveys. The focus of this article is on item non‐response which is often handled by filling in (or imputing) missing values using the observed responses (donors). Random imputation (single or fractional) is used within homogeneous imputation classes that are formed on the basis of categorical auxiliary variables observed on all the sampled units. A uniform response rate within classes is assumed, but that rate is allowed to vary across classes. We construct confidence intervals (CIs) for a population parameter that is defined as the solution to a smooth estimating equation with data collected using stratified simple random sampling. The imputation classes are assumed to be formed across strata. Fractional imputation with a fixed number of random draws is used to obtain an imputed estimating function. An empirical likelihood inference method under the fractional imputation is proposed and its asymptotic properties are derived. Two asymptotically correct bootstrap methods are developed for constructing the desired CIs. In a simulation study, the proposed bootstrap methods are shown to outperform traditional bootstrap methods and some non‐bootstrap competitors under various simulation settings. The Canadian Journal of Statistics 47: 281–301; 2019 © 2019 Statistical Society of Canada  相似文献   
859.
In this paper we study orthogonal main effect plans with four factors, A table of such designs, where each factor has at most 10 levels, and there are at most 40 runs, is generated. We determine the spectrum of the degrees of freedom of pure error for these designs.  相似文献   
860.
Left-truncated and right-censored (LTRC) data are encountered frequently due to a prevalent cohort sampling in follow-up studies. Because of the skewness of the distribution of survival time, quantile regression is a useful alternative to the Cox's proportional hazards model and the accelerated failure time model for survival analysis. In this paper, we apply the quantile regression model to LTRC data and develops an unbiased estimating equation for regression coefficients. The proposed estimation methods use the inverse probabilities of truncation and censoring weighting technique. The resulting estimator is uniformly consistent and asymptotically normal. The finite-sample performance of the proposed estimation methods is also evaluated using extensive simulation studies. Finally, analysis of real data is presented to illustrate our proposed estimation methods.  相似文献   
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