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51.
Estimation in the interval censoring model is considered. A class of smooth functionals is introduced, of which the mean is an example. The asymptotic information lower bound for such functionals can be represented as an inner product of two functions. In case 1, i.e. one observation time per unobservable event time, both functions can be given explicitly. We mainly consider case 2, with two observation times for each unobservable event time, in the situation that the observation times can not become arbitrarily close to each other. For case 2, one of the functions in the inner product can only be given implicitly as solution to a Fredholm integral equation. We study properties of this solution and, in a sequel to this paper, prove that the nonparametric maximum likelihood estimator of the functional asymptotically reaches the information lower bound. 相似文献
52.
H. P. Lopuhaä 《Statistica Neerlandica》1997,51(2):220-237
By means of a straightforward application of empirical process theory, we show that S-estimators of multivariate location and covariance are asymptotically equivalent to a sum of independent vector and matrix valued random elements respectively. This provides an alternative proof of asymptotic normality of S-estimators and clearly explains the limiting covariance structure. It also leads to a relatively simple proof of asymptotic normality of the length of the shortest α-fraction. 相似文献
53.
环境的变化要求相应的成本管理模式发生变革。本文首先分析了环境变化对企业成本管理的影响,之后对作业成本法的管理思想的前提假设进行分析,指出它对于现代企业成本管理的局限性及其产生这些局限性的主要原因。最后,在分析制约理论核心原理的基础上,提出了一种基于制约理论的成本管理模式,试图为研究适应现代企业的成本管理模式提供新的思路。 相似文献
54.
伴随着我国经济体制改革向纵深发展,国有企业负债比率过高的问题更加突出显示出来。为了解决这个问题,我国实施了“债转股”政策。本文讨论四个命题:(1)国有企业是负债比率过高还是收益率过低;(2)“债转股”政策究竟是使国有企业“财务解困”还是“体制解困”;(3)“债转股”政策究竟是转移金融风险还是化解金融风险;(4)资产管理公司为国有企业和国有商业银行解困,将来谁为资产管理公司解困。本文认为“债转股”政策设计存在功能缺陷与制度依赖。国有企业“债转股”政策的成功依赖于国有企业(商业银行)现代企业制度的建立与完善。 相似文献
55.
企业并购是企业进行资本扩张、促进企业间存量资源合理统流动的重要途径。对企业并购中的目标企企的选择、价值评估进行研究,构建我国企业并前过程中目标企业选择的评价指标体系,运用AHP法对目标企业选择进行定量化评估,将有利于企业通过并购后,实现资源的最优配置.保证企业经营机制协调、有效地运行。 相似文献
56.
57.
物流配送是一个涉及多种影响因素的综合性复杂问题。本文探讨了基于Agent(智能体技术)的物流配送决策支持系统设计,在该系统中的智能体模型中引入学习机制,初步建立了一个具有专家系统特点、可以不断进化的物流配送决策支持系统。 相似文献
58.
The exact forms of the locally minimum variance unbiased estimators and their variances are given in the case of a discontinuous
density function. 相似文献
59.
Robustness issues in multilevel regression analysis 总被引:8,自引:0,他引:8
A multilevel problem concerns a population with a hierarchical structure. A sample from such a population can be described as a multistage sample. First, a sample of higher level units is drawn (e.g. schools or organizations), and next a sample of the sub‐units from the available units (e.g. pupils in schools or employees in organizations). In such samples, the individual observations are in general not completely independent. Multilevel analysis software accounts for this dependence and in recent years these programs have been widely accepted. Two problems that occur in the practice of multilevel modeling will be discussed. The first problem is the choice of the sample sizes at the different levels. What are sufficient sample sizes for accurate estimation? The second problem is the normality assumption of the level‐2 error distribution. When one wants to conduct tests of significance, the errors need to be normally distributed. What happens when this is not the case? In this paper, simulation studies are used to answer both questions. With respect to the first question, the results show that a small sample size at level two (meaning a sample of 50 or less) leads to biased estimates of the second‐level standard errors. The answer to the second question is that only the standard errors for the random effects at the second level are highly inaccurate if the distributional assumptions concerning the level‐2 errors are not fulfilled. Robust standard errors turn out to be more reliable than the asymptotic standard errors based on maximum likelihood. 相似文献
60.
Since the year 2000, silicon intellectual property (SIP), which can minimize the gap in ‘design productivity’ that exists with systems-on-chip (SOC), has become one of the most important factors in the development of integrated circuit (IC) products in the SOC era. Although SIP is very important for IC industry development, complicated business, technical as well as legal issues inside SIP transactions have hindered successful transactions and the integration of SIPs into SOCs. Thus, web-based SIP e-Commerce mechanisms, called SIP Malls, have emerged, aiming to resolve complex SIP issues. To maintain its leading position and competitiveness in the World's IC industry, as well as the value added by SOC products in Taiwanese IC firms, the Taiwanese government has developed SIP Malls, using innovation policy tools. However, the Taiwanese SIP Mall industry remains immature. No existing Taiwanese SIP Malls generate a profit or account for a significant share of worldwide SIP transactions. This research will develop an analytical framework for defining an innovation policy portfolio that aims to develop Taiwan's SIP Mall industry, so that it will enhance the value added of SIP Malls and, thus, the nation's competitiveness in the SIP and IC industries, something which already has become one of the Taiwanese government's major concerns. The industry innovation requirements (IIRs) are summarized using the Delphi method. Meanwhile, the major IIRs identified by Decision Making Trial and Evaluation Laboratory (DEMATEL) are introduced. After the IIRs are derived, the relationships between the IIRs and innovation policy tools are derived by Grey relational analysis (GRA). Then, the innovation policy tools are clustered, based upon the Grey grades derived by GRA. Finally, reconfigured innovation policy portfolios are presented for the Taiwanese government's policy definition. The results demonstrate that developing an innovative policy portfolio that includes scientific, technical, educational, public enterprise, information, legal and regulatory, financial, and taxation policy tools will be the most necessary step towards developing Taiwan's SIP Mall industry. 相似文献