浅谈政策效应对居民消费空间差异性的影响     

傅有明 《四川三峡学院学报》2013,(2):37-41

采用面板随机效应模型,对我国东中西部政策效应对居民消费影响的空间差异性进行分析,根据研究结果发现：财政支出政策对居民消费的影响效果要远远大于财政收入政策效果;从城乡差异来看,财政政策对农村居民消费影响的效果较大,对城镇居民消费影响效果较小,这种特点特别表现在财政支出效果上;从区域差异上,财政支出政策对东部地区居民消费表现出更强的凯恩斯效应,对中西部地区居民消费则呈现更强的非凯恩斯效应,这种特征差异的原因可能是源于区域消费特征的差异;扩张财政政策在东中部效应显著,在西部紧缩性政策效果更为明显。  相似文献   

Measurement Bias Detection Through Factor Analysis     

Willem E. Saris  Albert Satorra  William M. van der Veld 《Structural equation modeling》2013,20(4):561-582

Assessing the correctness of a structural equation model is essential to avoid drawing incorrect conclusions from empirical research. In the past, the chi-square test was recommended for assessing the correctness of the model but this test has been criticized because of its sensitivity to sample size. As a reaction, an abundance of fit indexes have been developed. The result of these developments is that structural equation modeling packages are now producing a large list of fit measures. One would think that this progression has led to a clear understanding of evaluating models with respect to model misspecifications. In this article we question the validity of approaches for model evaluation based on overall goodness-of-fit indexes. The argument against such usage is that they do not provide an adequate indication of the “size” of the model's misspecification. That is, they vary dramatically with the values of incidental parameters that are unrelated with the misspecification in the model. This is illustrated using simple but fundamental models. As an alternative method of model evaluation, we suggest using the expected parameter change in combination with the modification index (MI) and the power of the MI test.  相似文献   

Diagnosing Global Case Influence on MAR Versus MNAR Model Comparisons     

Sonya K. Sterba  Nisha C. Gottfredson 《Structural equation modeling》2013,20(2):294-307

When missingness is suspected to be not at random (MNAR) in longitudinal studies, researchers sometimes compare the fit of a target model that assumes missingness at random (here termed a MAR model) and a model that accommodates a hypothesized MNAR missingness mechanism (here termed a MNAR model). It is well known that such comparisons are only interpretable conditional on the validity of the chosen MNAR model’s assumptions about the missingness mechanism. For that reason, researchers often perform a sensitivity analysis comparing the MAR model to not one, but several, plausible alternative MNAR models. In the social sciences, it is not widely known that such model comparisons can be particularly sensitive to case influence, such that conclusions drawn could depend on a single case. This article describes two convenient diagnostics suited for detecting case influence on MAR–MNAR model comparisons. Both diagnostics require much less computational burden than global influence diagnostics that have been used in other disciplines for MNAR sensitivity analyses. We illustrate the interpretation and implementation of these diagnostics with simulated and empirical latent growth modeling examples. It is hoped that this article increases awareness of the potential for case influence on MAR–MNAR model comparisons and how it could be detected in longitudinal social science applications.  相似文献   

类比推理的形式化探析     

胡毅敏 《昆明师范高等专科学校学报》2013,(1):55-57

类比推理是一种重要的推理,仅仅由属性的相似性去解释类比是不够的,应该从形式上对类比推理进行深入的探究.类比是源域S和目标域T之间的结构保持映射fM.在类比推理的过程中,对源域S的选择、对结构保持映射的要求以及对类比迁移的控制,都会影响类比推理的关联性和可靠性.  相似文献   

Accelerated matrix recovery via random projection based on inexact augmented Lagrange multiplier method     

王萍  张楚涵  蔡思佳  李林昊 《天津大学学报(英文版)》2013,19(4):293-299

In this paper, a unified matrix recovery model was proposed for diverse corrupted matrices. Resulting from the separable structure of the proposed model, the convex optimization problem can be solved efficiently by adopting an inexact augmented Lagrange multiplier (IALM) method. Additionally, a random projection accelerated technique (IALM+RP) was adopted to improve the success rate. From the preliminary numerical comparisons, it was indicated that for the standard robust principal component analysis (PCA) problem, IALM+RP was at least two to six times faster than IALM with an insignificant reduction in accuracy; and for the outlier pursuit (OP) problem, IALM+RP was at least 6.9 times faster, even up to 8.3 times faster when the size of matrix was 2 000×2 000.  相似文献   

疏影横斜水清浅 暗香浮动月黄昏——简评蒋冰的书法创作     

范进军 《娄底师专学报》2013,(5):65-67

蒋冰是近年来崛起的一位卓有成就的青年书法家。他的书法创作呈现出一种神清骨秀、高洁端庄、幽独超绝的气质风韵,具有极强的艺术审美价值。这与其深厚的文化底蕴、自然的创作理念、强烈的情感流露和执着的艺术追求密切相关。他的作品给当下书坛带来了一种不同凡响的清新气息。  相似文献   

大学与知识:重构智力城     

帕特丽夏·J·加姆波特  李春萍 《北京大学教育评论》2004,2(4):54-65

美国研究型大学遇到了挑战 :在经济与政治环境变化的情况下与知识变革保持同步 ,这要求它们在政府拨款以外创收并展示出对经济的直接贡献。基于一个跨度较大项目的比较个案研究 ,本文阐明了美国研究型大学的合法性基础如何在 2 0世纪最后 2 5年间发生变迁。在这个时代里 ,学术重构的组织话语开始进入一种产业逻辑 ,这一逻辑补充并在某些情况下成为“社会制度”逻辑的可行性选择。几种因素促成了产业逻辑获得优势 :资源匮乏的作用 (无论是实存的还是察觉的 )、政治行动者和广大公众对责任制需求的增长、重新阐释服务传统使技能训练和经济发展处于优先位置、管理科学作为一种意识形态的凸显、对于知识之适当价值的认可以及市场力量作为决策制定指南的合理性增强而相应地减少对专业自身的考虑。在指出这种适应的一般模式之外 ,本文还分析了与大学的独特传统和沿袭而来的学术结构相应的差异情形。  相似文献   

意愿调查法中的偏好不确定性研究综述     

苏红岩  王华 《资源科学》2019,41(12):2327-2341

对非市场物品和服务,如环境改善和资源保护,进行经济价值评估是学术界面临的一大难题。意愿调查法（Contingent Valuation Method, CVM）作为非市场物品经济价值评估的一种重要方法,其方法论在不断地接受检验并得到改进,近年来一个重要进展是其分析框架由确定偏好假设向不确定偏好假设转变。为系统认识国际上对CVM中受访者偏好不确定性的研究进展、推动国内相关研究,本文在简单介绍产生不确定结果的原因和不确定偏好假设下标准CVM不足的基础上,系统梳理了不确定偏好的测度方法和不确定偏好下价值计算方法,分析了各种方法的优劣以及考虑不确定性对价值估计值大小和估计效率的影响。总体来看,不确定偏好假设已基本形成共识,个人支付意愿应为随机变量也得到广泛支持。多数学者认为借助一定的测度技术获取的不确定性信息是有价值的,而如何更准确地测度和利用偏好不确定程度以提高资源环境等非市场物品价值估计效率应是今后研究的重点。最后,针对既有研究存在的问题,从加强个人偏好及不确定性的异质性研究、改进问卷设计等方面提出对未来研究工作的建议。  相似文献   

2001-2017年尼泊尔中部地区滑坡变化及其影响因素     

孙国庆  陈方  于博  王宁 《中国科学院大学学报》2020,37(3):308-316

滑坡是造成尼泊尔巨大经济损失和人员伤亡的主要地质灾害。目前，遥感方法对滑坡信息的识别、提取和监测具有巨大的潜力。基于随机森林模型的平均不纯度减少算法，选用NDBI、MNDWI、NDVI和红波段4个参数对Landsat遥感数据进行滑坡信息的初提取，同时借助目视解译得到滑坡的精提取结果。采用数据格网的方法将研究区划分为0.05°×0.05°的滑坡格网，并在不同土地覆盖类型中，对滑坡与降雨和温度进行偏相关分析。研究表明：1）尼泊尔中部地区的滑坡主要分布在海拔1 000~2 500 m，坡度20°~40°的范围内；2）相比其他土地覆盖类型，林地中滑坡数目与降雨的偏相关系数为0.671 5，而在草地中滑坡数目与温度的偏相关性最强，其偏相关系数为0.436 1；3）研究区片麻岩、页岩分布广泛，加之地震、断裂带、人类活动的影响，破坏边坡的稳定性，极易造成滑坡灾害。  相似文献   

The effect of toxicity on COVID-19 news network formation in political subcommunities on Reddit: An affiliation network approach     

《International Journal of Information Management》2021

Political polarization remains perhaps the “greatest barrier” to effective COVID-19 pandemic mitigation measures in the United States. Social media has been implicated in fueling this polarization. In this paper, we uncover the network of COVID-19 related news sources shared to 30 politically biased and 2 neutral subcommunities on Reddit. We find, using exponential random graph modeling, that news sources associated with highly toxic – “rude, disrespectful” – content are more likely to be shared across political subreddits. We also find homophily according to toxicity levels in the network of online news sources. Our findings suggest that news sources associated with high toxicity are rewarded with prominent positions in the resultant network. The toxicity in COVID-19 discussions may fuel political polarization by denigrating ideological opponents and politicizing responses to the COVID-19 pandemic, all to the detriment of mitigation measures. Public health practitioners should monitor toxicity in public online discussions to familiarize themselves with emerging political arguments that threaten adherence to public health crises management. We also recommend, based on our findings, that social media platforms algorithmically promote neutral and scientific news sources to reduce toxic discussion in subcommunities and encourage compliance with public health recommendations in the fight against COVID-19.  相似文献