Unification of Dirichlet Methodology

In this article we provide a unified framework for solving Dirichlet related probability and waiting time problems. We consider a Pólya sampling scheme in which each time an object is selected, it is put back into the population along with c additional objects of the same type. By considering both fixed sample size and inverse sampling procedures, we unify the Dirichlet I, J, C, and D functions with their hypergeometric counterparts by extending these functions to Pólya sampling. We then use these functions to unify and extend the corresponding expected waiting time results.     

THE CHOICE BETWEEN SETS OF REGRESSORS

This paper examines the choice of critical values for testing both non-sequential and nested sequential sets of constraints in the standard linear regression model. Modest increases in (e.g.) t-ratio critical values relative to their one-off values are often sufficient to maintain proper size. A Bayesian decision-theoretic approach, highlighted by the Schwarz (1978) criterion, provides a framework for deriving consistency and asymptotic local power properties of both forms of testing (data mining) algorithms.     

Estimating the distribution of one-dimensional discrete scan statistics viewed as extremes of 1-dependent stationary sequences

Discrete one-dimensional scan statistics can be viewed as extremes of 1-dependent stationary sequences. A result of Haiman [1999. First passage time for some stationary processes. Stochastic Process. Appl. 80, 231–248] provides approximations of the distributions of extremes of 1-dependent stationary sequences together with sharp bounds for the corresponding errors. We apply this result to scan statistics generated by Bernoulli r.v.'s and to the charge problem.     

Occupancy numbers for dynamic heterogeneous populations: Estimate of particles lifetimes

A dynamic model of a heterogeneous population is studied. Particles belonging to a population are divided, at every time t, into a finite number of classes according to their types and the partition changes over time. The role of the occupancy numbers, namely the cardinality of each class, is highlighted. The relationship between the stochastic process of occupancy numbers and the process of particle types is analyzed. The main goal of this paper is the estimation of the lifetime of each particle at a given time t, when the observed data are the history of the process of the number of dead particles up to t. Furthermore, a discrete time approximation of the filter is given.     

Considerations on group-wise identical designs for linear mixed models

We consider a general class of mixed models, where the individual parameter vector is composed of a linear function of the population parameter vector plus an individual random effects vector. The linear function can vary for the different individuals. We show that the search for optimal designs for the estimation of the population parameter vector can be restricted to the class of group-wise identical designs, i.e., for each of the groups defined by the different linear functions only one individual elementary design has to be optimized. A way to apply the result to non-linear mixed models is described.     

皮亚杰“儿童自我中心主义”概念评析

在皮亚杰的发生认识论学说中,“儿童自我中心”概念具有非常重要的意义。“儿童自我中心主义”表现在两个方面,即理智的自我中心和社会的自我中心。同时也表现在儿童心理发展的两个不同阶段,即感知-运动阶段和前运算阶段。皮亚杰指出:话动缺乏协调、主客体没有分化是心理上的自我中心状态的根源。儿童理智上的和社会的自我中心都是随着动作的逐渐协调而消逝的。如果仅从个体心理的基础来看,皮亚杰对儿童自我中心状态的根源的分析,以及他所指出的去除自我中心的途径,是基本正确的。但从社会心理机制的角度看,则存在一些明显的局限:明显的认知中心论,混淆了主客体关系与主体间关系,忽略了符号功能与摆脱社会的自我中心状态的内在联系。     

Mastering authority: J.M. Coetzee’s Diary of a Bad Year

J.M. Coetzee’s fiction has, from its inception, parodied language which claims to speak as the public use of reason. Diary of a Bad Year departs from this position to some degree by offering a series of public reflections on the times; however, these reflections are embedded within a narrative structure which disallows us from taking them at face value. Such narrative framing raises the question of authority: not only the authority of the reflections themselves, but the authority of the voice and the voice in the text. The relationship between fiction and the public sphere is such that fiction foregrounds the problem of authority in public discourse and seeks to capture the position of authority through heightened forms of mimesis and self‐consciousness.     

Does bullying reduce educational achievement? An evaluation using matching estimators

Using data from the Progress in International Reading Literacy Study (2006-PIRLS) and the Trends in International Mathematics and Science Study (2007-TIMSS), we investigate the determinants and the effect of being a victim of school bullying on educational achievement for Italian students enrolled at the fourth and eighth grade levels. Firstly, we apply an OLS estimator controlling for a number of individual characteristics and school fixed effects. Secondly, in order to attenuate the impact of confounding factors, we use propensity score matching techniques. Our empirical findings based on average treatment effects suggest that being a victim of school bullying has a considerable negative effect on student performance at both the fourth and the eighth grade level. Importantly, the adverse effect of bullying on educational achievement is larger at age 13 than at age 9. Hence, school violence seems to constitute a relevant factor in explaining student performance. Our findings suggest some possible interventions that Italian policy makers should adopt to prevent or reduce bullying behaviors.