The African Evaluation Guidelines: 2002. A checklist to assist in planning evaluations, negotiating clear contracts, reviewing progress and ensuring adequate completion of an evaluation

A review of the US ‘program evaluation standards’ (PES), undertaken in a series of workshops and meetings of networks of evaluators in Africa, resulted in modifications to those standards. The result was presented to a plenary session of the Inaugural Conference of the African Evaluation Association in September 1999, attended by over 300 evaluators from 35 countries. The AfrEA Conference decided that a systematic effort should be made to produce a list of African evaluation guidelines, similar to the PES, and that this checklist should be reviewed by national evaluation associations and networks in Africa and field tested in several countries. Ten national and regional networks and associations suggested modifications to the text and endorsed the final version of the guidelines.     

外向/内向型性格对外语学习的影响

外向/内向型性格与外语学习有相关关系,通过实验证明外向型性格能对外语学习产生积极影响。     

藏族学生英语教学的认知依据和认知准备

教学的良好效果在很大程度上取决于教学的各个环节是否与学习者的认知模式相吻合 ,和教学双方在教学活动中充分的认知准备。由于独特的自然、历史和文化的影响 ,藏族学生具有明显的神秘、具象、经验和“比量”的群体认知趋向。在把握这些认知趋向的基础上 ,藏族英语教学可分别从教师、学生、教材和对教学主体模式的预知等四个方面完成前教学阶段的认知准备。同时 ,应充分意识到教学中的民族性和独特性 ,从而有效地促进藏族学生的英语学习。     

Modelling daily multivariate pollutant data at multiple sites

Summary. This paper considers the spatiotemporal modelling of four pollutants measured daily at eight monitoring sites in London over a 4-year period. Such multiple-pollutant data sets measured over time at multiple sites within a region of interest are typical. Here, the modelling was carried out to provide the exposure for a study investigating the health effects of air pollution. Alternative objectives include the design problem of the positioning of a new monitoring site, or for regulatory purposes to determine whether environmental standards are being met. In general, analyses are hampered by missing data due, for example, to a particular pollutant not being measured at a site, a monitor being inactive by design (e.g. a 6-day monitoring schedule) or because of an unreliable or faulty monitor. Data of this type are modelled here within a dynamic linear modelling framework, in which the dependences across time, space and pollutants are exploited. Throughout the approach is Bayesian, with implementation via Markov chain Monte Carlo sampling.     

Computing maximum likelihood estimates from type II doubly censored exponential data

It is well-known that, under Type II double censoring, the maximum likelihood (ML) estimators of the location and scale parameters, θ and δ, of a twoparameter exponential distribution are linear functions of the order statistics. In contrast, when θ is known, theML estimator of δ does not admit a closed form expression. It is shown, however, that theML estimator of the scale parameter exists and is unique. Moreover, it has good large-sample properties. In addition, sharp lower and upper bounds for this estimator are provided, which can serve as starting points for iterative interpolation methods such as regula falsi. Explicit expressions for the expected Fisher information and Cramér-Rao lower bound are also derived. In the Bayesian context, assuming an inverted gamma prior on δ, the uniqueness, boundedness and asymptotics of the highest posterior density estimator of δ can be deduced in a similar way. Finally, an illustrative example is included.     

非统计专业统计学教育刍议

针对非统计专业统计学教育目前存在的问题,阐述了提高对统计学重要性的认识是保证统计教学效果的前提;统计学教学环节的改革是提高教学效果的重要保证;统计教师的业务素质是提高统计教学效果的关键。     

运用信息技术培养学生形象思维能力

从把握时机,掌握力度等方面提出遵循以学生为主体原则,符合学生认知过程的需要,同时保证语文教学按自身学科性质完成教学目标,在有利于学生形象思维发展的前提下,把握运用信息技术的最佳时机达到教学最佳效果.     

液相色谱串联质谱检测鳗鱼中四种氟喹诺酮残留

建立了液相色谱/串联质谱法测定鳗鱼中恩诺沙星,环丙沙星,诺氟沙星,氧氟沙星的方法。对分离和检测这四种兽药残留的液相色谱条件、质谱条件、样品前处理方法等作了详细的研究。用乙腈萃取样品中的残留物,在氮气保护下将萃取液浓缩干,加流动相1.0mL溶解残渣,正己烷液液萃取,弃上层液,下层溶液用作液相色谱分析荧光检测或质谱检测。在鳗鱼样品中添加四种残留物,添加浓度分别为0.01,0.050和0.100mg/kg,平均回收率(n=6)在70￣84.3%之间,相对标准偏差为3.0%～6.3%。     

Divergence-based estimation and testing with misclassified data

The well-known chi-squared goodness-of-fit test for a multinomial distribution is generally biased when the observations are subject to misclassification. In Pardo and Zografos (2000) the problem was considered using a double sampling scheme and ø-divergence test statistics. A new problem appears if the null hypothesis is not simple because it is necessary to give estimators for the unknown parameters. In this paper the minimum ø-divergence estimators are considered and some of their properties are established. The proposed ø-divergence test statistics are obtained by calculating ø-divergences between probability density functions and by replacing parameters by their minimum ø-divergence estimators in the derived expressions. Asymptotic distributions of the new test statistics are also obtained. The testing procedure is illustrated with an example.     

史料引用致误原因分析

史料是史学研究的基础.但自古以来,由于种种原因,错误的或者事实模糊不清的史料很多,如果不作必要的考证鉴别,很难获得科学的研究成果.造成史料引用致误的原因是多方面的,归结起来主要有:(1)史料本身无误,由于没有正确理解原意或者标点不正确而致误;(2)史料本身无误,由于引用者推断不确而致误;(3)史料内容比较含蓄,由于引用者缺乏深入辨析而致误;(4)没有直接引用原书而致误;(5)因版本不善而造成史料的错误或脱漏;(6)史料本身就有错误.