会计信息误差研究

会计信息误差可以分为有意误差和无意误差两大类。会计信息的有意误差就是会计造假,会计信息的无意误差并不一定是会计造假。会计信息的无意误差不可避免,只要是在信息需求者允许的误差范围内,这样的会计信息就应该被看作是＂真＂的会计信息。研究信息误差及其范围,对于保证会计信息的质量具有十分重要的意义。     

Tuning parameter selection in penalized generalized linear models for discrete data

In recent years, we have seen an increased interest in the penalized likelihood methodology, which can be efficiently used for shrinkage and selection purposes. This strategy can also result in unbiased, sparse, and continuous estimators. However, the performance of the penalized likelihood approach depends on the proper choice of the regularization parameter. Therefore, it is important to select it appropriately. To this end, the generalized cross‐validation method is commonly used. In this article, we firstly propose new estimates of the norm of the error in the generalized linear models framework, through the use of Kantorovich inequalities. Then these estimates are used in order to derive a tuning parameter selector in penalized generalized linear models. The proposed method does not depend on resampling as the standard methods and therefore results in a considerable gain in computational time while producing improved results. A thorough simulation study is conducted to support theoretical findings; and a comparison of the penalized methods with the L₁, the hard thresholding, and the smoothly clipped absolute deviation penalty functions is performed, for the cases of penalized Logistic regression and penalized Poisson regression. A real data example is being analyzed, and a discussion follows. © 2014 The Authors. Statistica Neerlandica © 2014 VVS.     

Regime-Dependent Relationships Between the Implied Volatility Index and Stock Market Index

We examine regime-dependent dynamics between Korea's representative implied volatility index (VKOSPI) and stock market index (KOSPI 200) using a two-regime threshold vector error correction model (TVECM). By analyzing high-quality daily data from January 2003 to June 2013, we make the following interesting observations based on a model with regime splitting. First, regardless of regime, we observe a negative contemporaneous correlation between the VKOSPI and KOSPI 200. Second, while the KOSPI 200 generally leads the VKOSPI under normal market conditions (lower regime), this relationship is overturned when market volatility measured by the VKOSPI level is extremely high (upper regime). Third, in the TVECM framework, the effects of lagged VKOSPI on the KOSPI 200 are positive only in the upper regime, while the effects of lagged KOSPI 200 on the VKOSPI are positive only in the lower regime; this cannot be explained by the traditional framework of an asymmetric volatility phenomenon. Fourth, the KOSPI 200 exhibits greater sensitivity to implied volatility shocks in the upper regime than it does to those in the lower regime.     

住房市场过度投资效应检验

为了验证对住房投资是否存在过度投资,通过对我国2001年第一季度至2011年第四季度的住房投资、非住房投资和总产出的协整检验、Granger因果检验和误差修正模型的估计,和两部门模型的建立、经验数据的模拟,其结果表明：（1）从长期协整关系看,中国经济增长受住房投资增长影响强烈,并且住房投资对非住房投资存在明显的＂挤出效应＂;（2）房地产部门资本边际收益率平均约为其他部门资本边际收益率的20%,房地产过度投资明显。回顾宏观经济的运行,认为住房投资推动通货膨胀增长的机制仍然存在,建议提高房地产保有成本,从而降低房地产需求,结合金融市场改革,国内经济结构调整才能实现。     

物理模型光谱模拟误差对冬小麦叶面积指数高光谱反演的影响

获取农作物叶面积指数(leaf area index,LAI)及其动态变化对于农作物长势监测和产量估测等应用具有重要的意义。基于冠层反射率模型(物理模型)的LAI遥感反演方法具有良好的普适性,对地面数据依赖较少,近年来广泛应用于农作物LAI高光谱反演研究。然而,当物理模型参数取值尽可能准确(代入参数实测值或依据先验知识取值)时,模拟光谱与实测光谱间仍然存在误差,研究称之为"光谱模拟误差"。该研究通过比对实测冬小麦冠层光谱与ACRM(a two-layer canopy reflectance model)模型最优模拟光谱,展示了光谱模拟误差在各波段、不同样本点的分布规律。据此,根据对光谱模拟误差与高光谱数据降维的不同考虑,制订了4种LAI反演波段选择方案。通过对比基于不同波段选择方案的LAI反演精度,分析了光谱模拟误差对LAI反演的影响;讨论了综合考虑高光谱数据降维与光谱模拟误差的LAI反演波段选择方法。通过合理的波段选择,限制了光谱模拟误差的影响,提高了LAI反演精度。该研究结果有助于探索合理的LAI高光谱反演波段选择方法,为合理利用高光谱数据反演农作物LAI提供科学参考。     

新疆农业资金投入与农民收入效应关系的实证研究

[目的]为清晰识别农业资金投入对新疆农民收入的影响程度,并给予地方政府进一步优化调整农业资金使用效能提供参考依据。[方法]文章选取1978~2013年新疆统计数据,采用协整分析、误差修正模型等方法对财政支农、农业贷款、农民自主投资与新疆农民人均纯收入进行了实证探究。[结果]新疆地区财政支农、农业信贷、农民自主投资与农民人均纯收入之间存在长期均衡关系;而短期内财政支农、农业信贷以及农户自主投资的促进效应不如长期明显,其中农业贷款的收入效应远低于财政支农和农民自主投资;财政支农、农民自主投资与农民人均纯收入在短期内具有格兰杰因果关系,长期则格兰杰因果关系解释力逐渐减弱,而农业贷款在短期内不是新疆农民人均纯收入增长的格兰杰原因,长期则互为格兰杰因果关系。[结论]该文提出加大财政支农投入力度,提高财政资金配置效率;推动农村金融改革,提高农村金融效率;提振农民自主积累资金投资的积极性等政策含义,以期为新疆"三农问题"有效解决提供坚实可靠的资本基础。     

Are Crop Yields Normally Distributed? A Reexamination

This article demonstrates that normality test procedures that include individual detrending of short-term panel data can severely reduce the power of normality tests and strongly bias normality tests in a Type II direction. An alternative error component implicit detrending procedure is suggested that demonstrates higher power for the distributions examined. Both procedures are applied to a large data set with normality of yield residuals being rejected. Assuming normality is shown to reduce potential premium rates for a large number of producers in an existing crop insurance product.     

基于ANSYS程序的锈蚀钢筋混凝土梁受弯承载力有限元分析

文章通过运用有限元软件ANSYS对锈蚀钢筋混凝土梁进行非线性分析,详细探讨了锈蚀混凝土和钢筋的本构模型、单元特性,并基于锈蚀钢筋与混凝土特殊粘结滑移理论,考虑锈蚀钢筋与混凝土之间的粘结作用。运用ANSYS进行锈蚀钢筋混凝土梁建模,进行有限元非线性分析。     

基于轮廓坐标的圆度误差3m评定法研究

本文通过比较几种评定圆度误差的方法,给出了其各自局限性。在介绍圆度误差3m点评定法的工作原理的基础上,给出了应用该评定法计算程序和算例,为进一步研究圆度误差的测量装置提供了理论依据。     

同步误差对OFDM系统的影响

OFDM系统相对于单载波系统来说,同步技术尤为关键。由于OFDM系统各个子载波间的正交性,使得OFDM系统对频率偏移非常敏感,为了保证系统性能的良好,我们要保证频率的稳定性。本文分析了同步误差对OFDM系统性能的影响,给出了一种新算法,仿真表明OFDM系统频率同步误差比时间同步误差对系统性能的影响要严重得多,只有当OFDM系统频偏小于0.02个子载波间隔时,系统才是处于稳定性能的,这时它所产生的ICI对系统的影响可以忽略不计。