Cross-Validated Assessments of Test Scoring Models

On a multiple choice test in which each item has r alternative options, a given number c of which are correct, various scoring models have been proposed. In one case the test-taker is allowed to choose any size solution subset and he/she is graded according to whether the subset is small and according to how many correct answers the subset contains. In a second case the test-taker is allowed to select only solution subsets of a prespecified maximum size and is graded as above. The first case is analogous to the situation where the test-taker is given a set of r options with each question; each question calls for a solution which consists of selecting that subset of the r responses which he/she believes to be correct. In the second case, when the prespecified solution subset is restricted to be of size at most one, the resulting scoring model corresponds to the usual model, referred to below as standard. The number c of correct options per item is usually known to the test-taker in this case.

Scoring models are evaluated according to how well they correctly identify the total scores of the individuals in the class of test-takers. Loss functions are constructed which penalize scoring models resulting in student scores which are not associated with the students true (or average) total score on the exam. Scoring models are compared on the basis of cross-validated assessments of the loss incurred by using each of the given models. It is shown that in many cases the assessment of the loss for scoring models which allow students the opportunity to choose more than one option for each question are smaller than the assessment of the loss for the standard scoring model.     

Nonparametric bayes estimation of the survival function from a record of failures and follow-ups

In some observational studies, we have random censoring model. However, the data available may be partially observable censored data consisting of the observed failure times and only those nonfailure times which are subject to follow-up. Suzuki (1985) discussed the problem of nonparametric estimation of the survival function from such partially observable censored data. In this article, we derive a nonparametric Bayes estimator of the survival function for such data of failures and follow-ups under a Dirichlet process prior and squared error loss. The limiting properties such as the mean square consistency, weak convergence and strong consistency of the Bayes estimator are studied. Finally, the procedures developed are illustrated by means of an example.     

Some results on renewal equations

In this paper solutions of renewal-type integral equations are studied. It is proved that a recursively spades;efined approximation to the solution has some nice convergence properties. Some simple bounds and other results on the renewal function and the renewal spades;,ensity are obtained.     

从高校毕业生看大学趋同现象

随着高等教育的大众化,大学生就业难已成为一种社会问题。越来越多的用人单位认为大学毕业生的技能和品质与其所要求的不相符合,而导致这种现象的重要原因之一是大学的日益趋同。在这种背景下,政府应加强进一步引导,通过深化改革人才培养模式、改革单一的评估体系、创办＂特色型＂大学等方式改变大学趋同现象,使大学绽放出独具特色的光芒。     

无穷级数比值判别法的推广

给出了正项级数关于敛散性的一个新的判别法 ,这一方法推广了达朗贝尔比值判别法     

人人参与，时时落实，处处渗透——实施美育的原则

美育究竟是不是一门专门化的独立课程,这个问题是涉及到美育如何实施的一个重要原则。从美育自身所具有的特点来看,它还不能说是一门固定的课。美育的要义是以美育人,但是,美却不是一种独立的物质现象,它是客观世界各种具体的事物和现象与社会人生的关系中所显示出来的一种价值,并且时时刻刻在人的精神生活中发挥着积极的作用。因此,美育不可能仅仅是一门具体的课,也不可能仅仅局限在课堂上,它主要还应该是通过一切教学活动,以一种处处渗透的方式来进行。可以这样说:哪里有美,那里就有美育活动。因此,美育的天地是无比广阔的,它是一项人人参与、时时落实、处处渗透的活动。     

商法的国际化

在阐述各国商法所具有同质性的基础上,以商法的国际化为例对商法国际化的原因、发展趋势等问题进行思考,得出随着市场经济的日益复杂和全球化,商法的趋同化成为未来商法发展的必然趋势,最后论述了中国的商事立法应面对这种现实,在商事立法中坚持国际性优先,兼顾处于市场经济初级阶段的实际的立法对策问题。     

Provincial Conditional Income Convergence in China, 1953-1997: A Panel Data Approach

This paper examines the tendency towards income convergence among China's main provinces during the two periods: the pre-reform period 1953-1977 and the reform period 1978-1997 using the framework of the Solow growth model. The panel data method accounts for not only province-specific initial technology level but also the heterogeneity of the technological progress rate between the fast-growing coastal and interior provinces. Estimation problems of weak instruments and endogeneity are addressed by the use of a system generalized method of moments (GMM) estimator. The main empirical finding is that there is a system-wide income divergence during the reform period because the coastal provinces do not share a common technology progress rate with the interior provinces.     

数字化对传媒生态的影响

传媒生态是指在一定时间和空间内传媒内部与外部各要素及其关系的总和。传媒生态受诸多因素的影响,而技术是其中最主要的因素之一。作为人类传播史上最重要的一次技术革命,数字化技术对传媒生态产生的巨大影响正日益显现。从传媒内生态和外生态两个视角,考察了数字化对整个传媒生态引发的变化及带来的影响。     

Conditional Functional Principal Components Analysis

Abstract.  This work proposes an extension of the functional principal components analysis (FPCA) or Karhunen–Loève expansion, which can take into account non-parametrically the effects of an additional covariate. Such models can also be interpreted as non-parametric mixed effect models for functional data. We propose estimators based on kernel smoothers and a data-driven selection procedure of the smoothing parameters based on a two-step cross-validation criterion. The conditional FPCA is illustrated with the analysis of a data set consisting of egg laying curves for female fruit flies. Convergence rates are given for estimators of the conditional mean function and the conditional covariance operator when the entire curves are collected. Almost sure convergence is also proven when one observes discretized noisy sample paths only. A simulation study allows us to check the good behaviour of the estimators.