一类四阶非线性常微分方程的两点边值问题解的存在性与唯一性

本文利用Hammerstein型积分算子和上下解方法,研究了一类四阶非线性常微分方程的两点边值问题     

Testing the Normality Assumption in the Tobit Model

This paper examines a number of statistics that have been proposed to test the normality assumption in the tobit (censored regression) model. It argues that a number of commonly proposed statistics can be interpreted as different versions of the Lagrange multiplier, or score, test for a common null hypothesis. This observation is useful in examining the Monte Carlo results presented in the paper. The Monte Carlo results suggest that the computational convenience of a number of statistics is obtained at the cost of poor finite sample performance under the null hypothesis.     

论工资率提高、通货膨胀与人民生活水平的改善——基于合肥市的实证研究

工资和物价水平是关乎民生的两个重要研究课题,稳定物价水平也是宏观经济政策的重要内容之一。随着国内物价水平不断上涨,通货膨胀预期不断递增,缓解人民生活压力和改善人民生活水平已经成为当前宏观调控的主要任务。对于通货膨胀的解释历来存在需求拉动型和成本推动型之争,对通货膨胀的不同解释意味着不同的宏观经济政策选择。利用构建联立方程组模型,将工资率和通货膨胀纳入同一个分析框架,模拟分析工资率与价格水平的之间关系。基于合肥市各部门相关数据的模拟结果显示,提高工资率和通货膨胀之间有一定的相关关系,这意味着通货膨胀包含工资成本推动因素,但是,模拟结果还显示工资的提高对经济发展的促进作用大于对价格的推动作用。     

An empirical investigation of different operating characteristics of several estimators of the intraclass correlation in the analysis of binary data

This paper is concerned with properties (bias, standard deviation, mean square error and efficiency) of twenty six estimators of the intraclass correlation in the analysis of binary data. Our main interest is to study these properties when data are generated from different distributions. For data generation we considered three over-dispersed binomial distributions, namely, the beta-binomial distribution, the probit normal binomial distribution and a mixture of two binomial distributions. The findings regarding bias, standard deviation and mean squared error of all these estimators, are that (a) in general, the distributions of biases of most of the estimators are negatively skewed. The biases are smallest when data are generated from the beta-binomial distribution and largest when data are generated from the mixture distribution; (b) the standard deviations are smallest when data are generated from the beta-binomial distribution; and (c) the mean squared errors are smallest when data are generated from the beta-binomial distribution and largest when data are generated from the mixture distribution. Of the 26, nine estimators including the maximum likelihood estimator, an estimator based on the optimal quadratic estimating equations of Crowder (1987), and an analysis of variance type estimator is found to have least amount of bias, standard deviation and mean squared error. Also, the distributions of the bias, standard deviation and mean squared error for each of these estimators are, in general, more symmetric than those of the other estimators. Our findings regarding efficiency are that the estimator based on the optimal quadratic estimating equations has consistently high efficiency and least variability in the efficiency results. In the important range in which the intraclass correlation is small (≤0 5), on the average, this estimator shows best efficiency performance. The analysis of variance type estimator seems to do well for larger values of the intraclass correlation. In general, the estimator based on the optimal quadratic estimating equations seems to show best efficiency performance for data from the beta-binomial distribution and the probit normal binomial distribution, and the analysis of variance type estimator seems to do well for data from the mixture distribution.     

心理资本与农民工工资收入的相互影响——以浙江省为例

利用来自浙江省微观层面农民工调查的数据,采用联立方程计量方法,本文实证考察了心理资本与农民工工资收入之间的相互关系。结果表明,心理资本与农民工工资收入之间存在联立性。心理资本对农民工工资水平产生了正向的显著影响,同时相对工资水平也显著影响了农民工的心理资本。人力资本(健康状况和教育年限)不仅对农民工的收入获得具有直接效应,而且还可以通过影响农民工的心理资本对其工资水平产生间接效应。     

Adolescents Leaving Parental Home: Psychosocial Correlates and Implications for Conservation

To disclose the interplay between psychosocial antecedents of adolescents' decisions to leave their parental home in an ecologically sensitive region, we used structural equation modeling to analyze data from in-person interviews of members of 220 households in Wolong Nature Reserve for giant pandas (China). We further divided our data into two sub-samples by gender to test the hypothesis that model parameters differ for females and males. Our findings indicate that parental attitudes/behavior, peer behavior, and perceived availability of material/non-material resources play a critical role in adolescents' home-leaving decisions. This study demonstrates an important link between psychosocial factors and biodiversity conservation.     

微机辅助试差法确定速度方程

众所周知,速度方程的确定是反应动力学的重要课题,其中的关键是确定反应级数。在确定反应级数的诸方法中,试差法长期被认为是笨拙而粗糙的方法。一些中外作者过去对试差法的评价为“方法繁杂,……不同级数往往难以区分。试差法一般适用于整数级”。“由于难于判断哪种关系图最接近于直线,因此使用试差法有很大的危险性,常常会得到错误的级数……”。然而,电子计算机的应用,使试差法面目一新。由于计算机运算快速可靠,且避去了人工作图、二次作图,目测渎图等过程,故它比微分法,半衰期法、坡威(Powell)作图法等快速准确。微机辅助试差法将优于确定反应级数的其它方法。     

Diagnostic tests as residual analysis

Many applied workers are strongly oriented to residual analysis for assessing model adequacy. Formal test statistics of adequacy however are frequently derived from likelihood theory, particularly through Lagrange Multipliers. In contraGt, the present paper derives the formal statistics by concentrating Upon the distribution of residuals. It is shown that most existing tests can be derived in this way from a few elementary principles of specification analysis. One advantage of this alternative methodology is that it highlights some difficulties in existing approaches and simultaneously indicates a resolution of them; a good example being testing for heteroscedasticity in simultaneous equations. Other issues such as independence and robustness of diagnostic tests are also easily explored within the proposed framework.     

非线性中立型差分方程的振动性

本文获得了非线性中立型差分方程振动的几个充分条件。     

Comments on “bootstrapping time series models”

Many applied workers are strongly oriented to residual analysis for assessing model adequacy. Formal test statistics of adequacy however are frequently derived from likelihood theory, particularly through Lagrange Multipliers. In contraGt, the present paper derives the formal statistics by concentrating Upon the distribution of residuals. It is shown that most existing tests can be derived in this way from a few elementary principles of specification analysis. One advantage of this alternative methodology is that it highlights some difficulties in existing approaches and simultaneously indicates a resolution of them; a good example being testing for heteroscedasticity in simultaneous equations. Other issues such as independence and robustness of diagnostic tests are also easily explored within the proposed framework.