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481.
Symmetric kernel smoothing is commonly used in estimating the nonparametric component in the partial linear regression models. In this article, we propose a new estimation method for the partial linear regression models using the inverse Gaussian kernel when the explanatory variable of the nonparametric component is non-negatively supported. As an asymmetric kernel function, the inverse Gaussian kernel is also supported on the non-negative half line. The asymptotic properties, including the asymptotic normality, uniform almost sure convergence, and the iterated logarithm laws, of the proposed estimators are thoroughly discussed for both homoscedastic and heteroscedastic cases. The simulation study is conducted to evaluate the finite sample performance of the proposed estimators. 相似文献
482.
纵向数据是随着时间变化对个体进行重复观测而得到的一种相关性数据,广泛出现在诸多科学研究领域。在对个体进行观测时,测量误差不可避免,忽略测量误差往往会导致有偏估计。本文利用二次推断函数方法研究关于纵向数据的参数部分和非参数部分协变量均含有测量误差的部分线性变系数测量误差(errors-in-variables, EV)模型的估计问题。利用B样条逼近模型中的未知系数函数,构造关于回归参数和B样条系数的偏差修正的二次推断函数以处理个体内相关性和测量误差,得到回归参数和变系数的偏差修正的二次推断函数估计,然后证明了估计方法和结果的渐近性质。数值模拟和实例数据分析结果显示本文提出的方法具有一定的实用价值。 相似文献
483.
学习能力倾向测验是目前国外应用得较为广泛的能力测验之一,在美国心理测验年鉴和一般的教科书中,与著名的韦氏智力测验和比纳智力测验一起划归为智力与学习能力倾向测验。文章在回顾国内外学业能力倾向测验的研究和应用现状的基础上。着重介绍学业能力倾向测验的特点、用途以及与其他相关测验的关系,以期对编制我国步学生适用的学业能力倾向测验做一准备和铺垫。 相似文献
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485.
Fushing Hsieh 《Journal of the Royal Statistical Society. Series B, Statistical methodology》2001,63(1):63-79
A class of non-proportional hazards regression models is considered to have hazard specifications consisting of a power form of cross-effects on the base-line hazard function. The primary goal of these models is to deal with settings in which heterogeneous distribution shapes of survival times may be present in populations characterized by some observable covariates. Although effects of such heterogeneity can be explicitly seen through crossing cumulative hazards phenomena in k -sample problems, they are barely visible in a one-sample regression setting. Hence, heterogeneity of this kind may not be noticed and, more importantly, may result in severely misleading inference. This is because the partial likelihood approach cannot eliminate the unknown cumulative base-line hazard functions in this setting. For coherent statistical inferences, a system of martingale processes is taken as a basis with which, together with the method of sieves, an overidentified estimating equation approach is proposed. A Pearson's χ2 type of goodness-of-fit testing statistic is derived as a by-product. An example with data on gastric cancer patients' survival times is analysed. 相似文献
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487.
Hui-Ming Wee Wan-Tsu Wang 《Omega》2012,40(3):264-266
In this note, we extend Pentico et al. (2011)'s [1] EPQ model where the authors considered two different backordering rates during shortage period; they assumed the backordering rate increases only from the start of production phase. We propose two models that allow the backordering rate to increase anytime during the production phase, and thus provide more flexibility for decision-makers to vary the backordering rate. 相似文献
488.
M. Ken Cor 《Social science research》2012,41(5):1003-1016
Survey researchers often administer batteries of questions to measure respondents’ abilities, but these batteries are not always designed in keeping with the principles of optimal test construction. This paper illustrates one instance in which following these principles can improve a measurement tool used widely in the social and behavioral sciences: the GSS’s vocabulary test called “Wordsum”. This ten-item test is composed of very difficult items and very easy items, and item response theory (IRT) suggests that the omission of moderately difficult items is likely to have handicapped Wordsum’s effectiveness. Analyses of data from national samples of thousands of American adults show that after adding four moderately difficult items to create a 14-item battery, “Wordsumplus” (1) outperformed the original battery in terms of quality indicators suggested by classical test theory; (2) reduced the standard error of IRT ability estimates in the middle of the latent ability dimension; and (3) exhibited higher concurrent validity. These findings show how to improve Wordsum and suggest that analysts should use a score based on all 14 items instead of using the summary score provided by the GSS, which is based on only the original 10 items. These results also show more generally how surveys measuring abilities (and other constructs) can benefit from careful application of insights from the contemporary educational testing literature. 相似文献
489.
以江苏省为例考察农户投资行为与金融支持的实证关系,通过误差修正模型和格兰杰检验等计量方法发现江苏省人均金融支持程度每提高一个百分点,当期农户人均投资量将增长0.55个百分点,同时两者呈现双向的G ranger因果关系,但农户人均投资增长率与人均金融支持增加量之间的长期均衡机制对农户投资行为的推动作用有限;根据实证结果提出相应的政策建议。 相似文献
490.
陈朝霞 《淮海工学院学报(社会科学版)》2013,(3):55-57
首先比较了船舶英语测试与以四六级为代表的普通英语测试、以商务英语为代表的人文英语测试和船舶专业知识测试的不同,以此界定船舶英语测试的特点。在语言测试效度整体观的理论框架中,选取验证效度最重要的内容相关证据分析了船舶英语测试的效度。 相似文献