Regression modelling of weighted κ by using generalized estimating equations

In many clinical studies more than one observer may be rating a characteristic measured on an ordinal scale. For example, a study may involve a group of physicians rating a feature seen on a pathology specimen or a computer tomography scan. In clinical studies of this kind, the weighted κ coefficient is a popular measure of agreement for ordinally scaled ratings. Our research stems from a study in which the severity of inflammatory skin disease was rated. The investigators wished to determine and evaluate the strength of agreement between a variable number of observers taking into account patient-specific (age and gender) as well as rater-specific (whether board certified in dermatology) characteristics. This suggested modelling κ as a function of these covariates. We propose the use of generalized estimating equations to estimate the weighted κ coefficient. This approach also accommodates unbalanced data which arise when some subjects are not judged by the same set of observers. Currently an estimate of overall κ for a simple unbalanced data set without covariates involving more than two observers is unavailable. In the inflammatory skin disease study none of the covariates were significantly associated with κ, thus enabling the calculation of an overall weighted κ for this unbalanced data set. In the second motivating example (multiple sclerosis), geographic location was significantly associated with κ. In addition we also compared the results of our method with current methods of testing for heterogeneity of weighted κ coefficients across strata (geographic location) that are available for balanced data sets.     

安徽省科技投入与经济增长的灰色关联研究

根据安徽省2000--2006年R＆D经费内部支出、科技活动人员投入和GDP的数据,对安徽省科技活动人员和R＆D经费内部支出的投入进行全面分析,并运用灰色相对关联度理论,分析了科技投入与经济增长的关系。结论表明：R＆D经费内部支出和科技人员投入与经济增长存在正相关关系,且R＆D经费内部支出对经济增长有着更为显著的促进作用。     

云南省丽江市农业生态系统协调度评价

以云南省丽江市农业生态系统为研究对象,根据农业生态系统特征将其划分为生态、经济和社会三个子系统,建立了关于该农业系统协调度的评价指标范畴,从系统指标体系中选取了19个代表性指标进行了实证研究。结果表明,该地区农业生态系统协调度在1998年-2007年间呈现上升趋势。1998年—2004年,系统呈现失调状态,协调等级在4级以下,2005年-2007年呈现弱度协调,协调等级为5级;系统的协调性主要受生态子系统和经济子系统的影响,在2004年之后,经济子系统和生态子系统的协调度与社会子系统的协调度的绝对值之差减小,农业生态系统由失调状态向协调状态发展。由此可知,经济与生态的协调是农业生态系统协调发展的核心。     

不同类别高校科技投入产出比较——基于近十五年（1992～2006）统计数据的分析

不同类别高校的科技投入、产出情况是反映科技工作整体格局的重要指标,文章以1992～2006年全国高校科技统计数据为依据,比较分析了不同类别高校的科技投入和科技产出。结果发现：不同类别高校之间的科技投入和科技产出差距明显;不同类别高校在科技产出上具有各自的相对优势;科技产出与科技投入之间存在强相关性。     

输入强化在多模态PPT演示中的实现

输入是语言习得发生的基础和前提,在二语尤其是外语课堂教学环境下,语言输入信息需要予以强化,以便增加被感知、注意、理解和内化的可能性。多模态PPT演示可以凭借相关技术手段,在视觉、音响以及二者结合的诸模态中有效实现对输入信息的强化。     

在线分类算法收敛性分析

文章研究基于凸损失函数的系数正则化在线算法误差分析,给出了欧式空间上的一种不依赖于样本空间容量的算法,并且根据步长的选择给出了相应的学习速率和错分类误差．     

风冷溴化锂吸收式制冷机热力－传热耦合性能的研究

本文结合各设备的传热性能，通过计算机模拟，以无量纲量Ｆ／Ｆ为变量研究风冷溴化锂吸收式制冷机的热力－传热耦合性能，据此求得各设备换热面积的合理匹配值．计算结果表明，风冷溴化锂机各设备换热面积经合理匹配，可以显著减小风冷吸收器和冷凝器的换热面积，机组单位基管面积制冷量可因此提高４７％，而机组的性能系数ＣＯＰ值与水冷溴化锂机基本接近．     

《农学报》中的生态思想探析

19世纪,中国现代化进程逐步启动,国外知识经验不断涌入,《农学报》在世纪末应运而生。当时人积极关注经济社会发展与生态环境的关系及发展可持续性问题,开展了许多思考和知识引进工作。他们强劲延续以往生态思想重在利用的主要方面,也浸染着现代社会更充分利用自然的理念、技术观点和竞争意识。《农学报》刊载的本国著述和译著有着诸多观点耦合,强调兴利求富的生产目标,对生态环境承载力、当时的人口增长和用化学方法实现合理农业持乐观态度,看重林业建设的直接经济利益并形成树种选择、林木抚育等方面的相应观点,要求增强社会治理能力以适应利用、保护自然之需。至于克服其中片面、机械的成份,容纳更多的生态保护内容以促进可持续发展,则是以后长期的任务。     

On Terrel's characterization of uniform distribution

Terrel (1983) (The Annals of Probability, Vol. 11, No. 3, 823–826) showed that the coefficient of correlation between the smaller and larger of a sample of size two is at most one-half, and this upper bound is attained only for continuous uniform distributions. His proof is of computational nature and is based on the properties of Legendre polynomials. We give an easier proof of Terrel's characterization and we show how our method can be used for obtaining sharper bounds within the class of discrete distributions onN points and also a characterization of the equidistant uniform distribution.