上海大学生就业状况调查

目前,上海大学生就业压力依然较大。上海要站在建设国际化大都市与推进城市全面转型的战略高度,合理架构体制机制,努力整合各类资源,采取有效措施,全面推进大学生就业工作。     

城市转型过程中的移民贫困问题与社会救助制度的应对

劳动力转移就业是推动城市化和城市转型的重要力量,但在城市转型过程中,产业结构的调整和升级可能会逐步压缩低技能转移劳动者的就业空间,导致结构性失业和贫困问题的恶化。作为现代社会应对贫困问题的主要制度安排,社会救助制度需要对此进行有效的调适。依据转移的福利驱动假设以及公民资格理论,本文对劳动力转移就业在贫困与社会救助领域所带来的主要问题,进行经验和理论层面的探讨。     

A permutation test approach to the choice of size k for the nearest neighbors classifier

The k nearest neighbors (k-NN) classifier is one of the most popular methods for statistical pattern recognition and machine learning. In practice, the size k, the number of neighbors used for classification, is usually arbitrarily set to one or some other small numbers, or based on the cross-validation procedure. In this study, we propose a novel alternative approach to decide the size k. Based on a k-NN-based multivariate multi-sample test, we assign each k a permutation test based Z-score. The number of NN is set to the k with the highest Z-score. This approach is computationally efficient since we have derived the formulas for the mean and variance of the test statistic under permutation distribution for multiple sample groups. Several simulation and real-world data sets are analyzed to investigate the performance of our approach. The usefulness of our approach is demonstrated through the evaluation of prediction accuracies using Z-score as a criterion to select the size k. We also compare our approach to the widely used cross-validation approaches. The results show that the size k selected by our approach yields high prediction accuracies when informative features are used for classification, whereas the cross-validation approach may fail in some cases.     

Approximate bounded influence estimation for longitudinal data with outliers and measurement errors

Mixed effects models or random effects models are popular for the analysis of longitudinal data. In practice, longitudinal data are often complex since there may be outliers in both the response and the covariates and there may be measurement errors. The likelihood method is a common approach for these problems but it can be computationally very intensive and sometimes may even be computationally infeasible. In this article, we consider approximate robust methods for nonlinear mixed effects models to simultaneously address outliers and measurement errors. The approximate methods are computationally very efficient. We show the consistency and asymptotic normality of the approximate estimates. The methods can also be extended to missing data problems. An example is used to illustrate the methods and a simulation is conducted to evaluate the methods.     

能源价格上涨情景下能源消费与经济波动的综合特征

 能源定价体制的改革是我国未来经济体制改革中一项非常重要、又极其紧迫的一项重大理论和实践课题,这一改革不但直接关系到我国经济增长和能源效率的提高效果,更是关乎我国经济发展转型的成败和我国未来能源安全的保障状况。通过建立CGE模型,本文研究了能源价格上涨情景下我国能源消费与经济增长的综合波动特征。主要发现如下：能源价格上涨虽然使得除进口外GDP、出口、就业等变量下降,物价水平上涨,但却能够在一定程度上降低能源强度并优化产业结构。就影响的大小而言,电力价格上涨的影响最大,石油和天然气次之,煤炭价格上涨的影响最小。从行业产出的变动来看,能源行业自身受能源价格上涨的负面冲击最大,其次是重工业,而农业、轻工业等所受的负面冲击最小。基于上述结论,我们认为,未来继续努力推进能源定价的市场化改革,是推进我国的节能降耗工作、提高经济增长效率的有效途径。     

基于极值Copula的投资组合集成风险度量方法

 应用极值的阈值与峰值模型来度量单个资产的风险价值,用两种不同的方法度量了基于Copula函数的沪深指数收益率的相关结构,比较了不同Copula函数下基于沪深指数的二元投资组合集成风险值,结果说明：Gauss Copula函数对沪深指数收益率的相关结构拟合较好,阈值模型的极值Copula能较好的度量投资组合的集成风险值,在高置信度下（0.99以上）,基于Gumble Copula函数的上尾（正收益）集成风险值、基于Clayton Copula函数的下尾（负收益）集成风险值与真实值最为接近。直接加权的方法会高估投资组合的风险,假设沪深指数的收益率服从二元正态分布会低估风险。峰值法的集成风险值误差较大。     

时变参数状态空间模型估计研究

在宏观经济和金融资本市场上广泛存在着非线性时变参数时间序列,而当前的研究主要关注静态参数状态空间模型的估计。本文通过引入变点分析,改进了静态参数的粒子学习滤波技术,提出了变点粒子学习滤波技术,用于估计时变参数状态空间模型。并且利用模拟实验同经典的变结构IMM滤波技术进行了对比,结果显示,本文提出的变点粒子学习滤波在动态模拟样本数据方面具有更大的优势。可以用于对股票价格和成交量的联合动态轨迹进行实时的模拟追踪。     

Extending the Mann–Whitney–Wilcoxon rank sum test to longitudinal regression analysis

Outliers are commonly observed in psychosocial research, generally resulting in biased estimates when comparing group differences using popular mean-based models such as the analysis of variance model. Rank-based methods such as the popular Mann–Whitney–Wilcoxon (MWW) rank sum test are more effective to address such outliers. However, available methods for inference are limited to cross-sectional data and cannot be applied to longitudinal studies under missing data. In this paper, we propose a generalized MWW test for comparing multiple groups with covariates within a longitudinal data setting, by utilizing the functional response models. Inference is based on a class of U-statistics-based weighted generalized estimating equations, providing consistent and asymptotically normal estimates not only under complete but missing data as well. The proposed approach is illustrated with both real and simulated study data.     

消费者偏好与真实生活成本

本文在消费者偏好结构可变的假设下,探讨了1998-2012年我国消费者真实生活成本。研究表明忽视消费者偏好结构的变化通常会高估消费者真实生活成本水平和增长幅度,而这种替代偏误的程度取决于基期的选择。基于这种研究发现,政府有关部门在使用消费者物价指数制定相关政策（尤其是福利政策）时,本文研究的非参数型真实生活成本指数 可能比一般的拉氏物价指数更为合适。因此,建议统计部门在使用拉氏价格指数统计消费者物价水平的同时,应该定期编制和公布 指数。