A lack-of-fit test for parametric zero-inflated Poisson models

Count data often contain many zeros. In parametric regression analysis of zero-inflated count data, the effect of a covariate of interest is typically modelled via a linear predictor. This approach imposes a restrictive, and potentially questionable, functional form on the relation between the independent and dependent variables. To address the noted restrictions, a flexible parametric procedure is employed to model the covariate effect as a linear combination of fixed-knot cubic basis splines or B-splines. The semiparametric zero-inflated Poisson regression model is fitted by maximizing the likelihood function through an expectation–maximization algorithm. The smooth estimate of the functional form of the covariate effect can enhance modelling flexibility. Within this modelling framework, a log-likelihood ratio test is used to assess the adequacy of the covariate function. Simulation results show that the proposed test has excellent power in detecting the lack of fit of a linear predictor. A real-life data set is used to illustrate the practicality of the methodology.     

Conditional expectation determination based on the J-process using Malliavin calculus applied to pricing American options

The aim of our paper is to elaborate a theoretical methodology based on the Malliavin calculus to calculate the following conditional expectation (P_t(X_t)|(X_s)) for s≤t where the only state variable follows a J-process [Jerbi Y. A new closed-form solution as an extension of the Black—Scholes formula allowing smile curve plotting. Quant Finance. 2013; Online First Article. doi:10.1080/14697688.2012.762458]. The theoretical results are applied to the American option pricing, consisting of an extension of the work of Bally et al. [Pricing and hedging American options by Monte Carlo methods using a Malliavin calculus approach. Monte Carlo Methods Appl. 2005;11-2:97–133], as well as the J-process (with additional parameters λ and θ) is an extension of the Wiener process. The introduction of the aforesaid parameters induces skewness and kurtosis effects, i.e. smile curve allowing to fit with the reality of financial market. In his work Jerbi [Jerbi Y. A new closed-form solution as an extension of the Black–-Scholes formula allowing smile curve plotting. Quant Finance. 2013; Online First Article. doi:10.1080/14697688.2012.762458] showed that the use of the J-process is equivalent to the use of a stochastic volatility model based on the Wiener process as in Heston's. The present work consists on extending this result to the American options. We studied the influence of the parameters λ and θ on the American option price and we find empirical results fitting with the options theory.     

大学英语词汇教学

教师期望效应和期望理论对大学英语词汇教学有重要的借鉴和指导作用。这些理论应用于大学英语词汇教学将有利于改进教学,同时要注意一些问题,以期更好地提高大学英语词汇教学的效果。     

理性分析通胀预期

2009年中国经济始终处在通缩阴影下,直到11月份CPI同比才转负为正,全年CPI-0.6%。2010年2月统计局发布统计数字显示,我国CPI同比增长2.7%,消费者也感受到物价飞速的上涨,因此引出全社会对通货膨胀预期形成的热烈讨论。其实我国通货膨胀预期在2009年已经出现,进入2010以来,通货膨胀预期加重。本文就是在此背景下分析了我国目前的通货膨胀预期。     

Parameter Estimation for a Bidimensional Partially Observed Ornstein–Uhlenbeck Process with Biological Application

Abstract. We consider a bidimensional Ornstein–Uhlenbeck process to describe the tissue microvascularization in anti‐cancer therapy. Data are discrete, partial and noisy observations of this stochastic differential equation (SDE). Our aim is to estimate the SDE parameters. We use the main advantage of a one‐dimensional observation to obtain an easy way to compute the exact likelihood using the Kalman filter recursion, which allows to implement an easy numerical maximization of the likelihood. Furthermore, we establish the link between the observations and an ARMA process and we deduce the asymptotic properties of the maximum likelihood estimator. We show that this ARMA property can be generalized to a higher dimensional underlying Ornstein–Uhlenbeck diffusion. We compare this estimator with the one obtained by the well‐known expectation maximization algorithm on simulated data. Our estimation methods can be directly applied to other biological contexts such as drug pharmacokinetics or hormone secretions.     

人民币升值预期与东南亚人民币化——基于小国视角跨期均衡货币替代模型的分析

通过建立东南亚国家代表性居民效用最大化的跨期均衡货币替代模型,我们发现人民币升值预期是东南亚人民币化的重要机遇。在此基础上,本文结合人民币持续升值的现实和不断强化的升值预期,进一步探讨了基于人民币升值预期背景的东南亚人民币化的可行策略。     

家庭经济地位与教育期望之间关系的实证研究

个体早期教育期望对于其未来教育地位具有重要影响。在前人对地位获得模型的研究基础上,以中国教育追踪调查数据CEPS（2013～2014基线数据）为样本,以中学生为研究对象,采用多元线性回归以及二元逻辑斯蒂线性回归方法,探讨了家庭收入对青少年教育期望的影响。研究发现:出生于家境贫寒的青少年,其教育期望年限更高,更期望上大学,希望接受硕士、博士等精英化教育;在职业教育与大学本科教育的选择中,家庭收入的影响不显著,表明青少年并没有因为其家庭条件不好就降低对自我的教育期望,选择进入次优的大学专科教育。研究结果表明,贫穷不一定导致青少年较低的教育期望,反而正是这种艰苦的家庭条件,对青少年起到了激励作用,使其对改变家庭命运、实现向上流动具有更强的信念,希望通过接受更高层次的教育,实现阶层的跃迁;对此的政策蕴含在于要积极创造条件,帮助寒门学子超越自身及家庭的不利条件,使之获得力争上游、实现高等教育梦的机会,促进社会合理有序的流动。     

接受美学视域下的汉英电影翻译

接受美学扬弃了＂文本中心论＂,确立了读者的中心地位,倡导把文学作品与读者的关系放到研究的首位,肯定读者对作品的意义和审美价值的建构意义。电影是一种属于大众化的传播媒介。任何高水平的译者在翻译过程中不仅需要具备很好的语言驾驭能力、文化理解力和艺术理解力,还要预见译语观众的期待视野,考虑他们的情感需求、语言和文化审美习惯等,让译语观众与原语观众的审美体验融为一体,而这些正是接受美学理论的核心魅力。     

R&D员工领导创新期望、内部动机与创新行为研究

在现代组织行为研究领域推动员工创造、创新的组织行为研究是一个热点问题。本文通过对我国跨地区企业研发员工的问卷调查研究对领导创新期望、员工内部工作动机及其创新行为间的关系进行了实证探讨。研究发现,在我国背景下,直属领导对下属员工的创新期望、员工之间横向交换对研发员工创新的行为都具有正向预测作用,其中员工内在工作动机在领导创新期望、员工横向交换对员工创新行为的作用路径关系中起到中介效应。本研究的调查结论不仅有助于加深我们对组织内员工创新行为推动和作用机制的深入了解,同时也会对我国企业,特别是高新技术企业推动员工创新的管理实践提供借鉴。