Threshold Estimation for Stochastic Processes with Small Noise

Consider a process satisfying a stochastic differential equation with unknown drift parameter, and suppose that discrete observations are given. It is known that a simple least squares estimator (LSE) can be consistent but numerically unstable in the sense of large standard deviations under finite samples when the noise process has jumps. We propose a filter to cut large shocks from data and construct the same LSE from data selected by the filter. The proposed estimator can be asymptotically equivalent to the usual LSE, whose asymptotic distribution strongly depends on the noise process. However, in numerical study, it looked asymptotically normal in an example where filter was chosen suitably, and the noise was a Lévy process. We will try to justify this phenomenon mathematically, under certain restricted assumptions.     

中国"十五"计划经济发展速度的引证

论证"十五"计划经济发展速度的前提是要正确分析和判断经济发展趋势、经济现象与经济规律的吻合程度,经济运行的工作质量和寻求解决问题的途径和办法。影响国内生产总值增长速度的因素有全社会固定资产投资总额、社会消费品零售总额、价格指数、进出口总额、实际利用外资、财政收入、居民储蓄和城镇居民人均可支配收入及农民人均纯收入八项。固定资产投资、消费品零售总额、进出口总额是经济增长可持续发展的关键因素,必须重视价格指数的正面影响,关注资本的投入量和资本的使用效率,关注财政投资对宏观调控能力的影响,增加城镇中低收入居民的可支配收入和增加农民收入是启动消费市场带动经济全面回升的重要步骤。     

《《报任安书》作于汉武帝太始四年补说》献疑

<报任安书>的写作年代历来有汉武帝太始四年和征和二年两说.徐朔方先生赞同王国维太始四年说并驳斥程金造<从报任安书商榷司马迁的卒年>有关征和二年的观点.分析各种史料,可以看出,徐先生由于在一些地方误读文献,加之忽略了一些历史和生活常识,故而其<补说>并不能够证明<报任安书>写于太始四年,因此赵翼和程金造关于<报任安书>写于征和二年的观点应是正确的.     

中国手机媒体发展前景分析

分析了日本I-MODE取得巨大成功的原因和不足之处,指出无论是从技术上还是从企业模式上,手机媒体在中国的发展都不可能直接拷贝I-MODE模式,只能以I-MODE为借鉴。中国电信发展迅速,手机媒体在中国现阶段发展的重点是手机短信,手机短信市场巨大,但在发展中也存在着一些问题,主要有虚假与不良信息传播、侵犯个人隐私、信息垃圾、信息安全等。然而可以预见,随着3G在中国的逐渐普及以及相关法规的完善,手机媒体将实现网络化、宽带化,将带来一个巨大的媒体市场。     

可以容忍的不平等：过渡与差别--柯亨思想的一种政治哲学考量

柯亨认为,马克思主义追求的社会主义理想是消除资本主义的阶级剥削,代之以经济平等和彻底的民主,但是,从历史和现实看,我们都距离马克恩的理想有很大距离。即使作为当前的合理目标是最好的选择,市场社会主义至多仍然是次优的选择。鉴于历史发展的进程要求,即过渡特征,我们必须对结果意义上的各种不平等采取包容政策。但在社会主义机会平等的条件下,收入差异在仅仅反映了不同的收入、闲暇差异时才是可以接受的。社会主义平等并非“机械的平等”或“结果的相同”。     

Saving behaviour and earnings uncertainty: Evidence from the British Household Panel Survey

For the first time, this paper uses a panel data set, the British Household Panel Survey, to analyse saving behaviour in Britain. One objective is to test the precautionary saving hypothesis, according to which households save to self-insure against uncertainty. Our results show that in accordance with this hypothesis, various measures of uncertainty based on earnings variability have a statistically significant effect on households' saving decisions. Moreover, in accordance with the life cycle model, households save more if they expect their financial situation to deteriorate. Received: 15 June 1999/Accepted: 4 January 2001     

Ecosystem resilience, specialized adaptation and population decline: A modern Malthusian theory

The purpose of this article is to construct a theoretical framework characterizing the interactions among economic development, ecosystem equilibrium and possible population decline, and to discuss the population dynamics in the very long run. In our framework, economic activities bridge population and environment. On the one hand, human beings reform the environment through economic activities; on the other hand, economic activities decrease environmental resilience and increase the possibility of an environmental change in a discontinuous and irreversible pattern, as described in Arrow et al. (1995). Furthermore, a highly developed economy also causes over-specialization of human adaptation, which tends to exaggerate the impact of an environmental change on human population size. Received: 19 January 1999/Accepted: 3 July 1999     

A two phases queueing system with Bernoulli vacation schedule under multiple vacation policy

This paper deals with a single server Poisson arrival queue with two phases of heterogeneous service along with a Bernoulli schedule vacation model, where after two successive phases service the server either goes for a vacation with probability p (0≤p≤1) or may continue to serve the next unit, if any, with probability q(=1−p). Further the concept of multiple vacation policy is also introduced here. We obtained the queue size distributions at a departure epoch and at a random epoch, Laplace Stieltjes Transform of the waiting time distribution and busy period distribution along with some mean performance measures. Finally we discuss some statistical inference related issues.     

The cost of children: May the collective approach to household behavior help?

The collective approach to household consumption behavior tries to infer from variables supposed to affect the general bargaining position of household members information on the allocation of consumptions goods and tasks among them. This paper investigates the extension of previous work to the case where children may be considered as a public consumption good by the two adult members of a household. The main question being asked is whether it is possible to retrieve from the aggregate consumption behaviour of the household and the relative earnings of the parents information on the allocation of goods between them and children. This alternative approach to the estimation of the ‘cost of children’ is contrasted with the conventional approach based on a ‘unitary’ representation of and demographic separability assumptions on household consumption behaviour. Received: 29 August 1997/Accepted: 26 November 1998