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排序方式: 共有360条查询结果,搜索用时 15 毫秒
1.
薛志红 《中北大学学报(社会科学版)》2002,(2):77-80
大学英语测试是大学英语教学中必不可少的一部分 ,合理的测试方法有助于推动教学质量的提高。通过对现行学期测试题型与内容优缺点的阐释 ,提出了改进学期测试的想法 ,并对学期测试中听力、阅读、词汇与结构、作文及口语的题型与内容以及评卷工作的改进进行了具体的探讨。 相似文献
2.
关于外语专业题库建设范式的探讨 总被引:2,自引:0,他引:2
杨朝军 《郑州航空工业管理学院学报(社会科学版)》2002,21(3):13-16
本文通过对当前国内外语教育形式的综览 ,指出了外语专业的题库建设已成为当务之急 ,并通过对各种考试形式的分析 ,提出了外语题库建设的具体理论模式———以项目反应理论为基础的计算机自适应测试。文章就有关方面的实施提出了自己的看法。 相似文献
3.
力学实验教学改革的探索与实践 总被引:1,自引:0,他引:1
力学实验作为力学课程中重要的实践性教学环节,对于培养工科学生用科学的方法来研究处理实际问题的能力和创新精神,提高学生的综合素质有着极其重要的作用.文章分析了力学实验教学改革的实践,探讨了提高力学实验教学效果的改革思路;提出要通过开发综合性与研究性实验项目,探索合理的实验教学模式,加强培养学生解决工程实际问题的能力及力学建模能力. 相似文献
4.
Standard algorithms for the construction of iterated bootstrap confidence intervals are computationally very demanding, requiring nested levels of bootstrap resampling. We propose an alternative approach to constructing double bootstrap confidence intervals that involves replacing the inner level of resampling by an analytical approximation. This approximation is based on saddlepoint methods and a tail probability approximation of DiCiccio and Martin (1991). Our technique significantly reduces the computational expense of iterated bootstrap calculations. A formal algorithm for the construction of our approximate iterated bootstrap confidence intervals is presented, and some crucial practical issues arising in its implementation are discussed. Our procedure is illustrated in the case of constructing confidence intervals for ratios of means using both real and simulated data. We repeat an experiment of Schenker (1985) involving the construction of bootstrap confidence intervals for a variance and demonstrate that our technique makes feasible the construction of accurate bootstrap confidence intervals in that context. Finally, we investigate the use of our technique in a more complex setting, that of constructing confidence intervals for a correlation coefficient. 相似文献
5.
研究需求受价格和商誉共同影响下易逝品动态定价与广告投资策略的联合决策问题。在初始库存确定的情形下,在某待定销售周期内,企业通过投入广告提升自身商誉从而拓宽市场,以企业利润最大化为目标,建立联合最优动态定价及广告投资策略模型。应用庞特里亚金极大值原理,求得不同系统参数下最优动态定价和广告投资策略及最优的销售周期。通过数值算例验证方法的有效性,结合参数灵敏度分析检验系统参数对最优策略的影响并给出相应管理意义。 相似文献
6.
Kevin Glazebrook Colin Paterson Sandra Rauscher Thomas Archibald 《Production and Operations Management》2015,24(2):311-324
Lateral transshipments are a method of responding to shortages of stock in a network of inventory‐holding locations. Conventional reactive approaches only seek to meet immediate shortages. The study proposes hybrid transshipments which exploit economies of scale by moving additional stock between locations to prevent future shortages in addition to meeting immediate ones. The setting considered is motivated by retailers who operate networks of outlets supplying car parts via a system of periodic replenishment. It is novel in allowing non‐stationary stochastic demand and general patterns of dependence between multiple item types. The generality of our work makes it widely applicable. We develop an easy‐to‐compute quasi‐myopic heuristic for determining how hybrid transshipments should be made. We obtain simple characterizations of the heuristic and demonstrate its strong cost performance in both small and large networks in an extensive numerical study. 相似文献
7.
Combining Inverse Probability Weighting and Multiple Imputation to Improve Robustness of Estimation 下载免费PDF全文
Peisong Han 《Scandinavian Journal of Statistics》2016,43(1):246-260
Inverse probability weighting (IPW) and multiple imputation are two widely adopted approaches dealing with missing data. The former models the selection probability, and the latter models data distribution. Consistent estimation requires correct specification of corresponding models. Although the augmented IPW method provides an extra layer of protection on consistency, it is usually not sufficient in practice as the true data‐generating process is unknown. This paper proposes a method combining the two approaches in the same spirit of calibration in sampling survey literature. Multiple models for both the selection probability and data distribution can be simultaneously accounted for, and the resulting estimator is consistent if any model is correctly specified. The proposed method is within the framework of estimating equations and is general enough to cover regression analysis with missing outcomes and/or missing covariates. Results on both theoretical and numerical investigation are provided. 相似文献
8.
顾晓云 《长江大学学报(社会科学版)》2006,29(2):77-80
目前工程项目管理存在的问题是项目预期性差,工程质量与经济效益难以协调,其根本的原因是运用经济手段管理项目的力度不够,造成工程的高投入与低产出;在管理方式上,行政命令过多,而经济杆杠发挥的作用不多。为了解决这些问题,必须运用经济的指标去管理与控制项目的运行。 相似文献
9.
从实体法角度来看,《合同法》第402条在法律适用上的漏洞,应以目的性扩张的方法完成漏洞之补充。其次,在仲裁程序中漏洞补充的实现也会遇到的一定的程序性障碍,应通过对仲裁规则的修改,达到解决这一问题的目的。 相似文献
10.
There has been increasing use of quality-of-life (QoL) instruments in drug development. Missing item values often occur in QoL data. A common approach to solve this problem is to impute the missing values before scoring. Several imputation procedures, such as imputing with the most correlated item and imputing with a row/column model or an item response model, have been proposed. We examine these procedures using data from two clinical trials, in which the original asthma quality-of-life questionnaire (AQLQ) and the miniAQLQ were used. We propose two modifications to existing procedures: truncating the imputed values to eliminate outliers and using the proportional odds model as the item response model for imputation. We also propose a novel imputation method based on a semi-parametric beta regression so that the imputed value is always in the correct range and illustrate how this approach can easily be implemented in commonly used statistical software. To compare these approaches, we deleted 5% of item values in the data according to three different missingness mechanisms, imputed them using these approaches and compared the imputed values with the true values. Our comparison showed that the row/column-model-based imputation with truncation generally performed better, whereas our new approach had better performance under a number scenarios. 相似文献