麦冬营养器官的相关关系

在麦冬营养器官相关关系中,分枝占主导地位。掌握好发育的阶段性,促进前期生长的营养根早生快发,争取分校数量,就能保证后期膨大块根个数相应增多。     

TEACHING STATISTICS: A TALK ABOUT TIME SERIES

When presenting research results to a mixed audience, it is common for seminar speakers either to address the specialists or the uninitiated (thus alienating the other, uncatered-for group of listeners), or to risk falling between these two stools (and so satisfy no one). We suggest a way that the lecturer's dilemma might often be more optimally resolved; and, in so doing, present material which could provide useful ideas for wider application in enlivening formal class-room instruction in time-series analysis. Finally, we pre-empt some of the predicted response that the content of this paper may trigger from certain experts; and discuss the general lack of emphasis on assumptions in statistical teaching.     

A Family of Correlation Coefficients Based on the Extended Gini Index

The extended Gini is a family of measures of variability which is mainly used in the areas of finance and income distribution. Each index in the family is defined by specifying one parameter, which reflects the social evaluation of the marginal utility of income. The higher the parameter, the more weight is attached to the lower portion of the cumulative distribution, reflecting higher concern for poverty. In this paper we list and investigate the properties of the equivalents of the correlation coefficient that are associated with the extended Gini family. In addition, we show that the extended Gini of a linear combination of random variables can be decomposed, in a way which is equivalent to the decomposition of the variance, with, in addition, terms that reflect additional properties of the random variables. The implication of these properties is that any decomposition that is performed with the coefficient of variation can be replicated by an infinite number of indices that are based on the Extended Gini coefficient.     

Test for the equality of several correlation coefficients

We derive two C(α) statistics and the likelihood-ratio statistic for testing the equality of several correlation coefficients, from k ≥ 2 independent random samples from bivariate normal populations. The asymptotic relationship of the C(α) tests, the likelihood-ratio test, and a statistic based on the normality assumption of Fisher's Z-transform of the sample correlation coefficient is established. A comparative performance study, in terms of size and power, is then conducted by Monte Carlo simulations. The likelihood-ratio statistic is often too liberal, and the statistic based on Fisher's Z-transform is conservative. The performance of the two C(α) statistics is identical. They maintain significance level well and have almost the same power as the other statistics when empirically calculated critical values of the same size are used. The C(α) statistic based on a noniterative estimate of the common correlation coefficient (based on Fisher's Z-transform) is recommended.     

A NEW PROCEDURE FOR ASSESSING LARGE SETS OF CORRELATIONS

In this paper, a new test of the hypothesis that all the correlations between a set of variables are zero is proposed. It is based on the asymptotic behaviour of the largest of the observed correlation coefficients. Here “asymptotic” refers to the size of the correlation matrix considered. Simulations show that the critical levels, calculated using the asymptotic theory, are conservative but quite accurate, even for small correlation matrices.     

资本结构的公司特征影响因素及其评价模型——来自中国上市公司的经验证据

运用资本结构理论,利用主成分和多元回归分析法,以我国上市公司为样本,实证研究了公司的控股股东结构、公司规模、盈利能力、成长性、资产结构、股权流通性、收入变异程度、非负债税盾和所得税等公司特征因素与其资本结构之间的关系,得出公司负债税盾与其负债水平正相关等七个重要结论;运用实证研究成果,建立我国上市公司资本结构的综合评价模型,并运用该模型求解出最优资本结构区间.     

Rank Tests for Clustered Survival Data

In a clinical trial, we may randomize subjects (called clusters) to different treatments (called groups), and make observations from multiple sites (called units) of each subject. In this case, the observations within each subject could be dependent, whereas those from different subjects are independent. If the outcome of interest is the time to an event, we may use the standard rank tests proposed for independent survival data, such as the logrank and Wilcoxon tests, to test the equality of marginal survival distributions, but their standard error should be modified to accommodate the possible intracluster correlation. In this paper we propose a method of calculating the standard error of the rank tests for two-sample clustered survival data. The method is naturally extended to that for K-sample tests under dependence.     

基于SSPD /PSS的机电产品设计方法研究

工程技术大学机械工程学院,上海201620） 摘要：针对传统产品服务系统( Product Service Svstem,PSS)下的机电产品设计过程缺乏智能化以及设计数据可靠性低的问题,提出了基于单一产品数据源( Single Source of Product Data,SSPD)的机电产品设计方法研究。构建产品服务关联性矩阵( Product Service Correlation Matrix,PSCM),在服务功能中提出产品技术性服务(Product Technical Service,PTS)的概念,并确定2种服务组合关系：互补关系和协同关系;同时以产品服务关联性矩阵和BOM映射理论为基础分别建立了产品BOM( P-BOM)、服务BOM(S-BOM)以及产品服务集成设计BOM( PSI-BOM)之间的逻辑关系和映射规则,并结合单一产品数据源技术理论实现机电产品的设计。最后,以电梯曳引系统为例,验证了该方法的可行性和有效性。本方法可提高机电产品设计的效率和可靠性。     

Distribution of the correlation coefficient for the class of bivariate elliptical models

We consider n pairs of random variables (X₁₁,X₂₁),(X₁₂,X₂₂),… (X_1n,X_2n) having a bivariate elliptically contoured density of the form where θ₁ θ₂ are location parameters and Δ = ((λ_ik)) is a 2 × 2 symmetric positive definite matrix of scale parameters. The exact distribution of the Pearson product-moment correlation coefficient between X₁ and X₂ is obtained. The usual case when a sample of size n is drawn from a bivariate normal population is a special case of the abovementioned model.     

我国社会科学证据发展状况初探

社会科学证据作为一种新型的证据手段,已经通过不同的证据形式在我国司法裁判中大量出现。这引起学界较多的关注和讨论,但在立法层面上和司法过程中却无法获取明确的信息。从这一现状的多方面原因中能够发现我国社会科学证据发展过程中自身和制度的困境,而美国关于社会科学证据相关性规则的经验值得思考和学习。