Testing homogeneity in semiparametric mixture case–control models

Parametric and semiparametric mixture models have been widely used in applications from many areas, and it is often of interest to test the homogeneity in these models. However, hypothesis testing is non standard due to the fact that several regularity conditions do not hold under the null hypothesis. We consider a semiparametric mixture case–control model, in the sense that the density ratio of two distributions is assumed to be of an exponential form, while the baseline density is unspecified. This model was first considered by Qin and Liang (2011 Qin, J., Liang, K.Y. (2011). Hypothesis testing in a mixture case–control model. Biometrics 67(1):182–198.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar], biometrics), and they proposed a modified score statistic for testing homogeneity. In this article, we consider alternative testing procedures based on supremum statistics, which could improve power against certain types of alternatives. We demonstrate the connection and comparison among the proposed and existing approaches. In addition, we provide a unified theoretical justification of the supremum test and other existing test statistics from an empirical likelihood perspective. The finite-sample performance of the supremum test statistics was evaluated in simulation studies.     

基于贝叶斯学习的惩罚因子的选择

文章基于贝叶斯学习,将正则化方法从贝叶斯分析的角度展开,在响应变量服从正态分布、回归系数服从指数型先验分布族的条件下,用贝叶斯准则给出了惩罚因子的取值与响应变量、系数的方差之间的关系,并将这一结果应用到岭回归和lasso回归中惩罚因子的选择.实例检验结果表明,当响应变量和系数服从正态分布,惩罚因子的值取二者方差商的方法比岭迹法和广义交叉验证法(GCV)拟合效果更优.     

北京金融"怎么看?""怎么办?"

以习近平总书记视察北京为标志,北京的城市功能定位和发展战略方向得到了明确,北京整个城市正在重新出发.作为北京第一大支柱产业,金融业的重新出发已刻不容缓.通过对北京金融业的雄厚基础、 得天独厚的发展优势、 北京金融业实现转型发展存在的短板进行梳理和分析,提出建设"首都型金融"的新目标和近期推动"首都型金融"发展的重点任务.     

Parameter estimation of a composite production function model based on improved artificial fish swarm algorithm and model application

The traditional Cobb–Douglas production function uses the compact mathematical form to describe the relationship between the production results and production factors in the production technology process. However, in macro-economic production, multi-structured production exists universally. In order to better demonstrate such input–output relation, a composite production function model is proposed in this article. In aspect of model parameter estimation, artificial fish swarm algorithm is applied. The algorithm has satisfactory performance in overcoming local extreme value and acquiring global extreme value. Moreover, realization of the algorithm does not need the gradient value of the objective function. For this reason, it is adaptive to searching space. Through the improved artificial fish swarm algorithm, convergence rate and precision are both considerably improved. In aspect of model application, the composite production function model is mainly used to calculate economic growth factor contribution rate. In this article, a relatively more accurate calculating method is proposed. In the end, empirical analysis on economic growth contribution rate of China is implemented.     

The heterogeneous impact of pension income on elderly living arrangements: evidence from China’s new rural pension scheme

This paper investigates the impact of pension income on living arrangements of the elderly. Taking advantage of a unique opportunity due to the recent establishment and expansion of the New Rural Pension Scheme in China, we explicitly address the endogeneity of pension status and pension income through a fixed-effect model with instrumental variable approach by exploiting exogenous time variation in the program implementation at county level. We find an overall positive effect of pension income on independent living as well as considerable heterogeneity. The positive income effects of the NRPS are concentrated among the elderly with adult children living nearby, of higher socio-economic status, and with better health at baseline; for other groups, the effects are insignificant. We also find that more generous programs exhibit larger effects. Our results highlight that living arrangement is multidimensional in rural China.     

Watching online videos interactively: the impact of media capabilities in Chinese Danmaku video sites

In China, the implementation of a Danmaku social media system to sustain and raise user interest in online video sites is an increasingly widespread phenomenon. Danmaku technology is used to display users’ messages in written text on the online video stream. Little is known about the effects of this form of interactive enhancement. The aim of this empirical study is to evaluate the evolving media capabilities of the Danmaku system and their effects on users’ perceptions of interactivity and their intentions to continue using Danmaku. We draw on media synchronicity theory and apply it to a stimulus-organism-response model. Using this framework, we hypothesize that the media capabilities of the Danmaku system, namely its transmission velocity, parallelism, symbol sets, rehearsability, and reprocessability, elicit increased interactivity, which influences users’ instantaneous intentions to share and to continue the use of the Danmaku system. The results showed that both users’ instantaneous intention to share and their intention to continue to use were significantly affected by the perceived interactivity. Unlike the results of previous studies, our findings showed that all five media capabilities positively affected the users’ perceptions of interactivity. The potential theoretical and practical implications of our findings are discussed.     

贝叶斯方法和频率方法比较研究

频率学派和贝叶斯学派作为统计推理中的两个最重要的方法,对于这两种对立的研究方式的站队选择显然影响着研究者的研究活动。占有霸主地位的频率学派尽管是后来者,显然占有着优势的地位,而今年以来贝叶斯方法的复苏,重新向频率派发起挑战。文章从概率的产生作为开始,简单地介绍了统计的发展历程,并分别对这两种方法选择的实用、重要的可操作标准给予分析,认为两种方法各有利弊,对两种方法的选择应结合实际情况选择。     

我国创业板市场的设立和风险投资退出机制

风险投资对于经济的增长尤其是高新技术的发展有非常重要的意义。而风险投资能够适时地成功退出,是其良好发展的关键。通过分析风险投资退出机制发现,我国新推出的创业板市场较低的上市条件．使风险投资更容易变现和退出。风险投资的不断发展,为创业板市场培育出优秀的上市资源。将创业板市场与风险投资退出机制结合,相辅相成,可以促进风险资金良性循环。     

解读王尔德唯美童话背后的呼唤

奥斯卡·王尔德是英国著名的唯美主义作家代表。他的童话用隐藏在童话外衣下的残酷折射了世间的冷酷和不公。在童话中,他始终贯彻唯关主义理念,对人物景致的刻画美轮美奂,而这唯美的刻画却总是逃脱不了死亡和悲惨的结局。完美的情节和悲惨的结局形成了强烈的反差,在这种反差之下读者的心被撕成了碎片;在美与丑的强烈对比中,读者与王尔德的呐喊产生了共鸣,听到了王尔德对于真善美无声的呼唤。     

新疆产业结构变迁与恩格尔系数协整关系的实证研究

通过构造一个由消费结构、城镇居民收入水平、第二产业结构和第三产业结构四个变量组成的VAR模型,对新疆城乡居民的消费结构与产业结构相互作用的关系及其动态特征进行了实证研究。根据设定的模型、格兰杰因果检验、脉冲响应函数、预测方差分解和协整检验,发现新疆城镇居民消费结构会影响第二产业结构的转换,随着居民收入水平的提高,恩格尔系数呈下降趋势。城乡居民收入水平对产业结构升级产生一定影响。