A likelihood ratio test for bimodality in two-component mixtures with application to regional income distribution in the EU

We propose a parametric test for bimodality based on the likelihood principle by using two-component mixtures. The test uses explicit characterizations of the modal structure of such mixtures in terms of their parameters. Examples include the univariate and multivariate normal distributions and the von Mises distribution. We present the asymptotic distribution of the proposed test and analyze its finite sample performance in a simulation study. To illustrate our method, we use mixtures to investigate the modal structure of the cross-sectional distribution of per capita log GDP across EU regions from 1977 to 1993. Although these mixtures clearly have two components over the whole time period, the resulting distributions evolve from bimodality toward unimodality at the end of the 1970s.     

A BETA-OPTIMAL TEST OF THE EQUICORRELATION COEFFICIENT

This paper considers the problem of testing for nonzero values of the equicorrelation coefficient of a standard symmetric multivariate normal distribution. Recently, SenGupta (1987) proposed a locally best test. We construct a beta-optimal test and present selected one and five percent critical values. An empirical power comparison of SenGupta's test with two versions of the beta-optimal test and the power envelope shows the relative strengths of the three tests. It also allows us to assess and confirm Efron's (1975) rule of when to question the use of a locally best test, at least for this testing problem. On the basis of these results, we argue that the two beta-optimal tests can be considered as approximately uniformly most powerful tests, at least at the five percent significance level.     

Exact testing in multivariate regression

An F statistic due to Rao (1951,1973) tests uniform mixed linear restrictions in the multivariateregression model. In combination with a generalization of the Bera-Evans-Savin exact functional relationship between the W, LR, and LM statistics, Rao's F serves to unify a number of exact test procedures commonly applied in disparate empirical literatures. Examples in demand analysis and asset pricing are provided. The availability of exact tests of restrictions in certain nonlinear models when the model is linear under the null, originally explored by Milliken-Graybill (1970), is extended to multivariate regression. Generalized RESET, J-, and Hausman-Wu tests are resented. As an extension of Dufour (1989), bounds tests exist for nonlinear and inequality restrictions. Applications include conservative bound tests for symmetry or negativity of the substitution matrix in demand systems.     

江苏省经济发展与城乡统筹关系实证分析：1980～2004

Granger因果关系检验表明,短期内江苏经济发展与城乡统筹存在着单向因果关系,长期内江苏的经济发展与城乡统筹之间存在着双向的、互为因果关系。进一步脉冲分析表明,一方面,经济发展并不会自动导致城乡差距的缩小,而且在长期还会进一步加大城乡差距;另一方面,在短期内城乡统筹水平对经济发展的影响并不显著,在长期内城乡统筹水平对经济发展的影响为负效应。     

基于虚拟仪器技术实现测试技术教学改革的研究

文章结合"机械工程测量与试验技术"课程实际章节内容,研究应用虚拟仪器技术,建立计算机辅助教学系统,实现融合性教学,为测试技术教学的改革提供论证和实例。     

Estimation of the number of studies with positive trends when studies with negative trends are present

A two-point estimator is proposed for the proportion of studies with positive trends among a collection of studies, some of which may demonstrate negative trends. The proposed estimator is the y-intercept of the secant line joining the points (a, F?(a)) and (b, F?(b)), where F?(p) is the empirical distribution function of p-values from one-tailed tests for positive trend derived from the individual studies. Although this estimator is negatively biased for any choice of the points 0 ≤ a < b ≤ 1, the bias is less than that of the previously proposed one-point estimator defined by setting b = 1. The bias of the two-point estimator is smallest when a and b approach the inflection point of the true distribution function, E [F?(p)]. The utility of the two-point estimator is demonstrated by using it to estimate the number of male-mouse liver carcinogens among carcinogenicity studies conducted by the National Toxicology Program.     

Computation of the percentage points and the power for the two-sided Kolmogorov-Smirnov one sample test

Two recursive schemes are presented for the calculation of the probabilityP(g(x)≤S _n (x)≤h(x) for allx∈®), whereS _n is the empirical distribution function of a sample from a continuous distribution andh, g are continuous and isotone functions. The results are specialized for the calculation of the distribution and the corresponding percentage points of the test statistic of the two-sided Kolmogorov-Smirnov one sample test. The schemes allow the calculation of the power of the test too. Finally an extensive tabulation of percentage points for the Kolmogorov-Smirnov test is given.     

健康动物肠菌群的毒性试验

1993年，作者从健康动物猪、鸡、兔、鱼等动物肠道中分离、鉴定出22株正常菌群，先后经过小鼠增重育肥试验、生物拮抗试验和肠菌群微囊化及保质观察的研究，筛选出12株优良菌株进行本次试验，试验结果表明．12株菌以不同菌量饲喂小鼠、雏鸡都显示出良好的安全性，未发现任何毒副作用。     

8种血清型禽大肠杆菌的生化反应及药物敏感试验分析

选取具有致病力8种血清（O1、O2、O6、O(35)、O(54)、O(55)、O(78)、O(103)）禽大肠肝菌进行生化反应及药物敏感试验，研究其生化特性及对药物的敏感性。结果表明：8种血清型大肠杆菌生化反应基本一致，所不同的是在卫予醇反应中，（O1、O2、O6、O(35)、O(105)）4种血清型大肠杆菌呈阴性；8种血清型大肠杆菌对了胶卡那霉素、痢特灵、链霉素、卡那霉素、新霉素、红霉素均呈极、高、中、低不同程度敏感，对万古霉素均不敏感；7种（除O6外）血清型大肠杆菌对氯霉素呈极敏感或高敏；6种（除O(35)、O(103)外）血清型大肠肝菌对庆大霉素呈高、中、低度敏感二种（O1、O2、O(54)、O(78)）血清型大肠杆菌对氨苄青霉素呈高度敏感；2种（O1、O2）血清型大肠杆菌对强力霉素、磺胺药、四环素呈中敏或极敏。     

石灰改良盐渍土路基工程特性试验研究

滨海盐渍土作为一种特殊土,具有溶陷、盐胀、腐蚀等不良的工程特性,滨海地区盐渍土路基填料是制约交通建设快速发展的重大岩土工程问题之一。为了解决滨海盐渍土的工程应用,基于大量的室内试验,研究分析了石灰改良盐渍土路基填料的液塑限试验、击实试验、室内CBR试验和不同条件的不固结不排水三轴试验结果,从工程技术、降低造价和环境保护等方面对滨海高速公路路基填料改良利用的可行性进行了研究论证,为滨海地区盐渍土路基的修筑具有重要的指导意义。