带多个变点的逐段连续线性分位数回归模型及应用

研究目标：建立具有多个变点的逐段连续线性分位数回归模型（Continuous Piecewise Linear Quantile Regression with Multiple Change Points,CPLQR）。研究方法：先通过LASSO和广义贝叶斯信息准则确定变点个数,再通过线性化技巧来估计变点的位置与回归系数。研究发现：新方法能够同时确定变点个数、估计变点位置和回归系数,而且具有较强的稳健性;应用该方法于年龄和身体质量指数之间关系,进一步证实了模型的实用性。研究创新：新方法能够处理多个变点的问题,通过LASSO和广义贝叶斯信息准则确定变点数目,避免了主观判断的弊端;借助线性化技巧,解决了目标函数在变点处不可导问题。研究价值：本文结果将为分析经济、金融、医药和生物等学科中存在结构变化的数据提供强有力的研究工具。     

中国外商直接投资与环境污染的内在机理研究

随着经济的发展,中国环境污染问题日益突出。若从国际经济学角度出发,外商直接投资是会改善中国环境质量还是会加剧中国的环境污染呢?本论文利用1994—2008年相关数据,采用平稳性检验、协整性检验和格兰杰因果检验的方法,研究表明:外商直接投资是工业废水排放和工业固体废物排放的格兰杰原因,且呈负相关关系,说明外商直接投资改善中国环境质量,但外商直接投资与工业二氧化硫排放之间不存在因果关系。     

Thinning and harvesting in stochastic forest models

This paper analyzes a stochastic forest growth model in which the manager is able to first thin the forest to promote better growth before harvesting. Both Wicksell single thinning and harvesting cycle and Faustmann on-going rotation problems are considered. The Wicksell problem is analyzed by first restricting the class of decision times to (thinning, harvesting) pairs that bound the growth away from infinity and imbedding the problem in an infinite-dimensional linear program on a space of triplets of measures. These measures capture the thinning and harvesting decisions along with the behavior of the growth process prior to harvest. An auxiliary linear program then leads to a nonlinear optimization problem for which an optimal value and solution are determined. The values of all the problems are be related through a set of inequalities. The solution of the nonlinear problem determines (random) thinning and harvesting times for the single thinning and harvesting cycle which demonstrate the equality of the values of these various problems. Finally for the Wicksell problem, the unrestricted class of thinning and harvest times is shown to give the same value as the restricted class. The Faustmann on-going thinning and harvesting rotation problem is reduced to a Wicksell problem which then allows for the characterization of the value as the solution to a different nonlinear optimization problem. The effects of the opportunity to thin the forest are illustrated on a mean-reverting stochastic model.     

SEASONALITY,FORECAST EXTENSIONS AND BUSINESS CYCLE UNCERTAINTY

Abstract Seasonality is one of the most important features of economic time series. The possibility to abstract from seasonality for the assessment of economic conditions is a widely debated issue. In this paper we propose a strategy for assessing the role of seasonal adjustment (SA) on business cycle measurement. In particular, we provide a method for quantifying the contribution to the unreliability of the estimated cycles extracted by popular filters, such as Baxter and King and Hodrick–Prescott (HP). The main conclusion is that the contribution is larger around the turning points of the series and at the extremes of the sample period; moreover, it much more sizeable for highpass filters, like the HP filter, which retain to a great extent the high‐frequency fluctuations in a time series, the latter being the ones that are more affected by SA. If a bandpass component is considered, the effect has reduced size. Finally, we discuss the role of forecast extensions and the prediction of the cycle. For the time series of industrial production considered in the illustration, it is not possible to provide a reliable estimate of the cycle at the end of the sample.     

人民币汇率波动与通货膨胀率之间关系的实证分析

本文试图回答以下问题:人民币升值可以替代通货膨胀吗?如果可以,定量的替代关系如何?在综合使用了多种分析方法后,我们发现人民币升值在某种程度上确实可以抑制国内价格水平的上涨,但其效果决定了升值不能成为抑制通胀的主要工具。另外,通过模型我们还揭示出劳动生产率的提高对于国内物价的上涨具有决定性意义。     

A characterization of admissible linear estimators of fixed and random effects in linear models

In the paper the problem of simultaneous linear estimation of fixed and random effects in the mixed linear model is considered. A necessary and sufficient conditions for a linear estimator of a linear function of fixed and random effects in balanced nested and crossed classification models to be admissible are given.     

Akaike-type criteria and the reliability of inference: Model selection versus statistical model specification

Since the 1990s, the Akaike Information Criterion (AIC) and its various modifications/extensions, including BIC, have found wide applicability in econometrics as objective procedures that can be used to select parsimonious statistical models. The aim of this paper is to argue that these model selection procedures invariably give rise to unreliable inferences, primarily because their choice within a prespecified family of models (a) assumes away the problem of model validation, and (b) ignores the relevant error probabilities. This paper argues for a return to the original statistical model specification problem, as envisaged by Fisher (1922), where the task is understood as one of selecting a statistical model in such a way as to render the particular data a truly typical realization of the stochastic process specified by the model in question. The key to addressing this problem is to replace trading goodness-of-fit against parsimony with statistical adequacy as the sole criterion for when a fitted model accounts for the regularities in the data.     

新型农村合作医疗制度的农民满意度研究——对“新农合”试点县(电白县)的一项问卷调查

新型农村合作医疗制度从2003年试点至今,已处于全面覆盖状态。广东省电白县为实施该制度的一个试点县,2008年达到100%的参合率,但近年来参合率有所下降。文章通过实地走访谈话、设计并派发调查问卷等方式,找寻新型农村合作医疗的参合率下降的原因,通过调查数据整理,建立线性回归模型进行分析。分析结果显示,与新型农村合作医疗的满意度明显相关的因素是参合者的年龄、对新型农村合作医疗的了解度及对新型农村合作医疗的认可度。建议通过加强宣传力度、提高报销比例、扩大报销范围等进一步完善新型农村合作医疗制度。     

中国保险业发展影响因素实证分析

本文研究了现阶段影响我国保险业发展的主要因素,并通过建立计量分析模型进行了实证分析,结果显示现阶段我国保险业的发展主要受居民收入水平、社会固定资产投资以及通货膨胀的影响,其中居民收入水平、社会固定资产投资与保险市场成正相关的关系,通货膨胀与其成负相关的关系。     

AMR语音编码算法研究及复杂度剖析

作为 3GPPWCDMA的语音编码 (SpeechCoding)候选方案 ,自适应多速率 (AMR)语音编码是一种多模式集成的ACELP类语音编码方案。本文根据该编码方案的标准 ,分析了其方案实现中的关键算法 :高性能码本设计、高效码本搜索算法、多级矢量量化技术、预处理算法的简化等。最后 ,设计了定点ANSI -C程序对AMR语音编码算法各部分的复杂度进行了测算