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101.
Growth in U.S. agriculture is linked to the non-farm economy through domestic terms of trade and factor market adjustments. With almost stable input growth, the relatively large contributions from growth in Total Factor Productivity (TFP) are passed on to intermediate and final consumers in the form of declining real prices for primary farm products. The resulting net growth in the real value of farm output (GDP) is relatively low (0.25% per annum). The decomposition of TFP suggests that public agricultural stock of knowledge and infrastructure are robustly associated with TFP growth, while spill-overs from private agricultural and economy wide research and development (R and D) are positive but, relatively small.  相似文献   
102.
4D技术在工程项目管理中的应用和发展趋势   总被引:2,自引:0,他引:2  
丁卫平  陈建国 《基建优化》2004,25(4):1-4,12
现代建设工程日趋复杂,传统的工程项目管理思想和手段已经无法满足项目业主越来越高的要求,进度、成本和质量管理彼此独立的传统模式导致许多弊端,主要表现在各专业生成的软件信息不能共享、项目参与各方所拥有的知识和经验不能很好地提供项目决策支持。随着管理思想、管理理论、IT技术的飞速发展,运用产品数据建模、软件集成(3D 成本/进度)的思想和方法,对传统管理工具进行变革成为可能。本文引进工程项目集成化管理思想,分析国内外4D技术研究的情况,提出4D建模技术辅助工程项目管理的发展方向和趋势。  相似文献   
103.
针对R&D项目投资的特点,探讨了采用布莱克一舒尔斯期权定价模型对R&D项目价值评估可能存在的缺陷,并提出一种改进方法,即将决策树和布莱克一舒尔斯定价模型结合运用,因为决策树能够模拟研发项目的阶段性决策过程,考虑到多个离散型不确定性因素的相关性,模拟并计算出对决策路径依赖的现金流,因此能克服纯粹使用布莱克一舒尔斯公式的不足,在考虑多个不确定性因素的影响下,实现对多阶段R&D项目价值的评估,作出正确的投资决策。  相似文献   
104.
Measuring volatility with the realized range   总被引:1,自引:0,他引:1  
Realized variance, being the summation of squared intra-day returns, has quickly gained popularity as a measure of daily volatility. Following Parkinson [1980. The extreme value method for estimating the variance of the rate of return. Journal of Business 53, 61–65] we replace each squared intra-day return by the high–low range for that period to create a novel and more efficient estimator called the realized range. In addition, we suggest a bias-correction procedure to account for the effects of microstructure frictions based upon scaling the realized range with the average level of the daily range. Simulation experiments demonstrate that for plausible levels of non-trading and bid–ask bounce the realized range has a lower mean-squared error than the realized variance, including variants thereof that are robust to microstructure noise. Empirical analysis of the S&P500 index-futures and the S&P100 constituents confirms the potential of the realized range.  相似文献   
105.
This paper explores the impact of copyrights on firm value and on the demand for firm output. Using panel data on franchise value and ticket sales from the National Football League over the 1991–2000 period, we analyze the effect of copyrights (in this case, team logos) using several parametric estimators, the Arellano and Bond [1991. Some tests of specification for panel data: Monte Carlo evidence and an application to employment equations. Review of Economic Studies 58, 277–297] dynamic panel data estimator, and a semi-non-parametric method based on difference-in-differences propensity score matching. We find a negative effect of logo changes on franchise value that is robust across multiple specifications. In addition, logo changes also appear to have a moderate positive, albeit not particularly robust, impact on ticket sales.  相似文献   
106.
We examine the impact of short sellers on insider trading profitability using a natural experiment of a pilot program which relaxed short-selling constraints for randomly selected pilot stocks. We find that pilot firms experienced a significant decrease in insider trading profitability during the pilot program. The results are more pronounced for the pilot firms with poor information quality, and for the pilot firms without corporate restrictions on insider trading. Our evidence suggests that short sellers serve an important market disciplinary role by reducing insider trading profitability.  相似文献   
107.
We study the effects of terrorist attacks on firms’ long-term annual management earnings forecasts bias. We find that the managers of firms located closer to the epicenters of attacks are more likely to issue optimistic long-term annual earnings forecasts relative to the managers of a control group of unaffected firms. The exposure effect is stronger for more severe terrorist events, and firms with more uncertain fundamentals and less geographic diversification. In addition, we document that managers’ forecast optimism intensifies for firms with stronger negative stock market reaction to the terrorist event, for CEOs with higher ability and for companies that are more likely to issue equity or engage in acquisitions following the terrorist event. Overall, our results are consistent with the idea that long-term annual earnings forecasts are used by managers to counterbalance the short-term pessimistic response to terrorist attacks.  相似文献   
108.
合作R&D是企业整合研发资源的有效组织形式。本文对产业组织角度的合作R&D研究进行了较为细致的综述。首先列举了对合作R&D理论具有一定影响的经验研究;然后梳理了产业组织角度的合作R&D主流理论;之后介绍了较有代表性的非主流理论研究;最后是全文结论和留待进一步研究的论题。  相似文献   
109.
Abstract. I evaluate a new German regulation that requires retail discounters to guarantee the availability of their products in bargain sales. The regulation is meant to prevent loss leaders. Retailers undermine the regulation's rationale by claiming that rationing is due to demand uncertainty. This paper shows that under demand uncertainty the regulation has ambiguous welfare effects. Effectively, it raises production, which, under imperfect competition, tends to be beneficial. However, the regulation overshoots and decreases welfare if it requires availability for a state of high demand that is relatively unlikely. In this case more sophisticated regulation is required.  相似文献   
110.
This paper responds to the unsatisfactory argument that there is no correspondence between co-integration and the efficient market hypothesis. A law of one co-integrating vector of prices is proposed for the exchange rate and domestic and overseas stock prices. Markets must therefore be efficient in long-run equilibrium because no arbitrage opportunities exist. However, arbitrage activity via the disequilibrium error correction allows above-average (risk-adjusted) returns to be earned in the short run. The elimination of these arbitrage opportunities means that stock market inefficiency in the short run ensures stock market efficiency in the long run.  相似文献   
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