The geometry of Gaussian double Markovian distributions

Gaussian double Markovian models consist of covariance matrices constrained by a pair of graphs specifying zeros simultaneously in the matrix and its inverse. We study the semi-algebraic geometry of these models, in particular their dimension, smoothness, and connectedness as well as algebraic and combinatorial properties.     

Estimation of a Conditional Copula and Association Measures

Abstarct. This paper is concerned with studying the dependence structure between two random variables Y ₁ and Y ₂ conditionally upon a covariate X. The dependence structure is modelled via a copula function, which depends on the given value of the covariate in a general way. Gijbels et al. (Comput. Statist. Data Anal., 55, 2011, 1919) suggested two non‐parametric estimators of the ‘conditional’ copula and investigated their numerical performances. In this paper we establish the asymptotic properties of the proposed estimators as well as conditional association measures derived from them. Practical recommendations for their use are then discussed.     

条件逻辑及其部分定理的证明与阐释

条件逻辑是以充分条件、必要条件、充分必要条件以及它们之间相互关系为研究对象的逻辑理论。运用现代逻辑的手段,深入研究各种条件联系及其它们相互之间的逻辑关系,这对提高我们的认识能力、有效从事实践具有指导意义。在给出的定义的基础上．我们可以证明有关充分条件、必要条件、充分必要条件的大量定理,条件逻辑就是由定义和定理所构成的形式系统。     

源于斯金纳强化理论的大学英语多媒体课件效果提高策略

作为一种语言学习和教学理论,“强化理论”阐述了外语学习过程中的一种规律性的内在因素。同时,它可以使语言教师加深对外语教与学本质的认识。在深入剖析以操作性条件反射为核心的强化学习理论内涵的基础上,针对大学英语多媒体课件的现状,并根据英语学习者的心理,提出提高大学英语多媒体课件效果的策略。     

Compulsory Income Management in the Northern Territory – evaluating its impact

Australia has been experimenting with constraining the ways in which welfare recipients can spend their income support payments, limiting their ability to access cash and purchase some products. The policy objectives include to reduce spending on alcohol, gambling, pornography and tobacco in favour of meeting ‘basic’ family needs, especially for children, to limit the scope for financial harassment, encourage pro‐social behaviours, and build financial capabilities. In the logic of the programs these outcomes are expected to be manifest at the individual, family and community levels. The policy has primarily impacted on Indigenous Australians as a result of its geographic targeting, although a recent report has recommended a more stringent version of the program be introduced universally to all welfare recipients other than the aged. The largest of these experiments is ‘New Income Management’ in the Northern Territory, which has had more than 35,000 participants since its introduction in 2010. This article reports on the key findings of the major independent evaluation of New Income Management commissioned by the Australian Government.     

Non‐parametric Estimation of Extreme Risk Measures from Conditional Heavy‐tailed Distributions

In this paper, we introduce a new risk measure, the so‐called conditional tail moment. It is defined as the moment of order a ≥ 0 of the loss distribution above the upper α‐quantile where α ∈ (0,1). Estimating the conditional tail moment permits us to estimate all risk measures based on conditional moments such as conditional tail expectation, conditional value at risk or conditional tail variance. Here, we focus on the estimation of these risk measures in case of extreme losses (where α ↓0 is no longer fixed). It is moreover assumed that the loss distribution is heavy tailed and depends on a covariate. The estimation method thus combines non‐parametric kernel methods with extreme‐value statistics. The asymptotic distribution of the estimators is established, and their finite‐sample behaviour is illustrated both on simulated data and on a real data set of daily rainfalls.     

Covariate Decomposition Methods for Longitudinal Missing‐at‐Random Data and Predictors Associated with Subject‐Specific Effects

Investigators often gather longitudinal data to assess changes in responses over time within subjects and to relate these changes to within‐subject changes in predictors. Missing data are common in such studies and predictors can be correlated with subject‐specific effects. Maximum likelihood methods for generalized linear mixed models provide consistent estimates when the data are ‘missing at random’ (MAR) but can produce inconsistent estimates in settings where the random effects are correlated with one of the predictors. On the other hand, conditional maximum likelihood methods (and closely related maximum likelihood methods that partition covariates into between‐ and within‐cluster components) provide consistent estimation when random effects are correlated with predictors but can produce inconsistent covariate effect estimates when data are MAR. Using theory, simulation studies, and fits to example data this paper shows that decomposition methods using complete covariate information produce consistent estimates. In some practical cases these methods, that ostensibly require complete covariate information, actually only involve the observed covariates. These results offer an easy‐to‐use approach to simultaneously protect against bias from both cluster‐level confounding and MAR missingness in assessments of change.     

通过课堂互动减少大学校园里的偏见和歧视

偏见和歧视是社会心理学中的两个概念,在学习过程中,采用课堂讨论这种互动方式,使同学们跳出书本内容的局限,从知识的概念、社会现实中的表现、产生的原因、如何减少偏见和歧视这四个方面去理解和探索,师生共同探讨减少偏见和歧视的方法,可达到减少大学校园里同学之间存在的偏见和歧视的效果.     

论间接故意犯罪的未完成形态

我国刑法理论通行的观点是否定间接故意犯罪存在未完成形态的.但本文从现实案例入手,结合对案例的分析,对通行观点进行了质疑,阐述了间接故意犯罪未遂与中止的成立.     

A method for estimating parameters and quantiles of the three-parameter inverse Gaussian distribution based on statistics invariant to unknown location

The inverse Gaussian (IG) distribution, also known as the Wald distribution, is a long-tailed positively skewed distribution and a well-known lifetime distribution. In this paper, we propose an efficient method of estimation for the parameters and quantiles of the three-parameter IG distribution, which is based on statistics invariant to unknown location. Through a Monte Carlo simulation study, we then show that the proposed method performs well compared with other prominent methods in terms of bias and variance. Finally, we present two illustrative examples.