次贷危机、信息不对称和指数交易

次贷危机源于房价上涨停滞后的次贷及其衍生品市场的快速萎缩,信息不对称在危机爆发前风险累积阶段和危机后市场过度反应阶段都是关键因素.次贷及其衍生产品设计繁复且对房价系统性下跌高度敏感,次贷的衍生产品多在场外市场交易使得危机前相关信息未被充分披露.随着指数交易的陆续推出,如基于次债的ABX.HE指数和CME的房地产价格指数期货期权合约,使房价、次贷及其衍生产品的概括性信息得以揭示,基于信息不对称因素的恐慌加重了危机程度.综上,本文针对衍生品设计和市场的完善提出了建议.     

近60年“二十四节气”起源地气温与降水时空变化特征

目的 “二十四节气”长期以来对晋南农业生产起着重要的指导作用,探究其气候变化特征对农业适应性耕作和种植结构调整存在潜在影响。方法 文章选取1961—2020年尧都区、翼城县、侯马市3个气象代表站逐日气温、降水资料,采用线性趋势、滑动平均、Mann-Kendall分析、F检验等方法,对二十四节气气温、降水时空分布特征及变化趋势进行分析。结果 （1）研究区二十四节气的气温、降水均呈准正态单峰型分布,大暑气温最高,小寒气温最低,降水主要集中在夏至至秋分节气之间。（2）二十四节气的平均气温均呈上升趋势,其中冬季和春季型节气升温趋势极显著,秋季型节气升温趋势显著,夏季型节气升温趋势不明显;最低气温升温趋势极显著,有21个节气升温趋势通过0.01水平的显著性检验;最高气温升温趋势不明显。雨水是一年中升温最大的节气,平均气温变化率为0.729℃/10年（P<0.001）。（3）多年来研究区年平均降水量呈减少趋势,谷雨和夏至两个节气降水减少趋势显著（P<0.05）。（4）反映降水的7个节气平均气温均呈显著升温趋势,升温突变时间集中在20世纪90年代末。反映物候的4个节气中,惊蛰和清明升温趋势极显著,5年平均气温滑动曲线变化为两峰两脊型,2000年以前为相对偏冷期,2000年以后为相对偏暖期;小满和芒种节气升温趋势较弱,20世纪80—90年代有明显谷值区,2000年以后气温明显升高。结论 春初、秋末节气气温显著升高,作物生长季延长,研究成果对适应气候变化,合理利用气候资源,适时调整农事活动和种植结构具有一定的指导意义。     

多元线性回归模型在市场比较法中的应用

市场比较法是房地产估价中的最重要的方法。通过收集市场交易案例对房地产价格与其影响因素进行线性拟合得到计算某类房地产价格的通用方程，对拟合交易案例的选择，影响因素的量化，回归模型的建立和解算，房地产价格的确定分别作了具体阐述。     

大连市城市人居环境与产业结构关系定量研究

城市人居环境的影响因素多样,涉及自然环境、社会经济发展水平等主要方面。社会经济因素中的产业结构是城市人居环境的决定性因子之一;运用主成分分析方法以大连市为实证分析产业结构与人居环境之间的关系,并建立了数学模型;研究结果表明:产业结构中,第三产业对城市人居环境的影响最大,其原因为:①第三产业本身的服务业性质即直接提高了人居环境;②第三产业推动经济发展间接改善人居环境;③第三产业本身污染小,对人居环境的负面影响小;据此提出了大连市今后应大力调整产业结构,发展第三产业,促进人居环境的发展,形成第三产业与人居环境相互促进、良性循环的局面。     

美元汇率对中国天然橡胶现货价格影响的实证

2009年以来天然橡胶价格的大涨大落无法用天然橡胶的基本供求解释;在2009年1月至2015年5月美元指数和中国全乳胶价格的周度数据,在单位根和协整检验基础上,构建向量自回归(VAR)模型,利用脉冲响应函数和Granger因果检验对全乳胶价格与美元指数之间的关系进行分析;结果表明:美元指数与全乳胶价格之间存在负相关关系,且在Granger意义上因果单向相关,即美元指数的变化会影响全乳胶价格,但全乳胶价格的变化不会影响美元指数;该结果能较好地解释2009年至今天然橡胶价格大涨大落现象。基于研究从微观和宏观提出政府应鼓励企业加强套期保值交易、利用关税、国家收储等政策应对美元汇率对中国天然橡胶市场的影响。     

The efficiency of composite weather index insurance in hedging rice yield risk: evidence from China

As an economic and market‐transparent program, weather index insurance is expected to mitigate asymmetric problem. Capturing the relationship between yield and weather factor(s) is the basis of index insurance, but remains a challenge for weather index schemes. Meanwhile, composite weather index insurance is needed by farmers when their agricultural activities involve several risks, but is rarely studied. We aim to design a composite weather index insurance model and evaluate its efficiency in hedging yield risk by using the case of rice production in China. We divide the whole growth cycle of rice into six stages on the basis of agronomic knowledge, and use the average value of each weather factor in each stage to design a weather index. Then, the efficiency of composite weather index insurance is evaluated by mean‐semivariance and value‐at‐risk methods. First, we find that subdivision of the growth cycle helps to better capture the subtle relationship between rice yield and weather factors. Second, composite weather index insurance evidently reduces yield risk. Our findings help further adoption of weather index insurance in agricultural fields.     

长江中游城市群区域经济差异及其时空演化特征

以1999年至2006年各城市人均GDP为测度指标,采用传统统计方法和地统计方法,在Arcgis及GeoDa等软件的支持下,计算出长江中游地区城市群的标准差、变异系数、泰尔指数及Moran’s I值,并分析其空间自相关性,从时间和空间的角度分析区域经济差异。研究表明:区域经济总体发展水平不断上升,差异缓慢扩大,有空间聚集趋势,但趋势不明显,中心城市的扩散效应不强,带动作用不明显。     

中国小麦主产区生产效率时空演变特征分析

[目的]基于2006—2015年我国15个小麦主产省(区)小麦生产投入产出数据,对小麦主产区生产效率时空演变特征进行分析。[方法]利用数据包络分析(DEA)、Malmquist指数模型以及探索性空间分析(ESDA)对我国小麦生产效率演变的时空异质性进行研究。[结果](1)在时间异质性方面,2006-2015年我国小麦主产区小麦生产的综合技术效率均值为0. 928,纯技术效率均值为0. 943,规模效率均值为0. 984,均未达到有效水平,主产区小麦全要素生产率变化指数介于0. 920和0. 977之间,全要素生产率的增长受到了技术进步更大的制约。(2)在空间异质性方面,不同省(区)在纯技术效率存在较为明显的空间异质性,而在规模效率方面则较为接近。在全要素生产率方面,超过半数的研究省(区)小麦全要素生产率呈现负增长的趋势。(3)在生产效率的空间相关性方面,我国小麦主产区的小麦生产效率整体上呈现出较为显著的空间集聚效应,相较于其他地区而言,黄淮海小麦优势区存在较为显著且稳定的空间正相关关系。[结论]因地制宜地发挥区域生产禀赋优势、提高小麦主产区技术的有效投入,是提高小麦生产效率的关键,同时,通过资源合理配置实现小麦生产的空间布局优化,是整体提升我国小麦生产效率、维护粮食市场稳定的关键。     

Nonparametric estimates of productivity and efficiency change in Australian Broadacre Agriculture

This paper computes and decomposes Färe‐Primont indexes of total factor productivity of Australian broadacre agriculture by estimating distance functions. Using state‐level data from 1990 to 2011, the empirical results show that TFP grew at an average rate of 1.36 per cent per annum in the broadacre agriculture over the period 1990–2011. There are variations of total factor productivity (TFP) growth across states and fluctuations over time within each state and territory. However, overall, there is a clear movement towards slower TFP growth across the sample period. Further decomposition of TFP growth shows that it is declining growth in technical possibilities (technological progress) that is the main driver of the declining trend in productivity growth in broadacre agriculture in Australia.     

The identification and assessment of ecological risks for land consolidation based on the anticipation of ecosystem stabilization: A case study in Hubei Province,China

The purpose of this study is to identify and classify the ecological risks in land consolidation, and to develop a framework of the theory and method to assess the change of ecological risk degree before and after land consolidation. Environmental impacts and ecological risks of land consolidation have recently drawn much attention, and there are two opposing viewpoints to assess these impacts and risks in the academia of China. Both viewpoints result from the bias of assessment anticipation. Land consolidation includes four main engineering aspects in China, and ecological succession from start of land consolidation to ecosystem stabilization should pass three phases. Different ecological impacts and risks of land consolidation rise from different phases of ecological successions. According to the climax theory of ecology, we developed a framework of the ecological risk assessment based on the anticipation of ecosystem stabilization (ERABAES) for land consolidation. We applied analytical hierarchical processing (AHP) method to the data resources from the land consolidation project in Southern China to allocate weightings to the indices of ecological risk (ER), and to set up an integrated index system for the ecological risk identification. This integrated index system encompasses the ecological risks with three factors (water, soil and biology) and 14 indices. The results of the project show: (1) The ER is reduced from 58.02 to 28.8 after land consolidation and the degree of ecological risk is down from Degree III to Degree IV. (2) According to the element analysis, the water ER is reduced from 21.53 to 6.16, its contribution to reduce the ecological risk is 53%; the reduced ERs of soil and biology are respectively 12.79 and 1.06, their contribution of ecological risk reduce is lower than water.