- 2023.02.12
高佳、荣鹰,自然灾害对企业价值的实质影响——基于中国上市公司地震公告的事件研究,管理科学学报,2022,25(04)
【论文摘要】自然灾害能对企业造成相当的影响,自然灾害的风险管理不容忽视.衡量自然灾害对企业造成的实质性影响,是从企业层面对自然灾害进行风险管理的前提.本文以地震为例,收集我国上市公司于2008年~2015年间发布的,关于企业生产运营是否受到地震灾害影响的公告,定位可能受到实质影响的企业,利用事件研究法,估计地震给企业造成的实质影响。首先,结合已有研究的结论,对研究情境和样本可能存在的情绪性影响进行逐一讨论和检验,未发现有显著的情绪性影响的存在。然后,估算得受影响公告公布当天,样本企业市值平均损失2%,一周内平均损失2.5%,基于多重检验,该损失可以被认为是地震对企业造成的实质影响。此外,还检验了突发事件情境下,我国股票市场的半强有效性,发现市场反应及时,不存在逆转,且可以区分不同信息,说明该情境下我国“股票市场半强有效”假设成立.前述研究结果稳健。
- 2022.10.25
梁枫,学术期刊对学科建设的支撑能力研究:基于第五轮学科评估的内容分析,科技与出版. 2022,(06)
【论文摘要】学术期刊与学科建设具有学术共同体属性,学术期刊对学科建设的支撑能力是该学术共同体的重要一极。文章从学科办刊的角度,结合国内学科建设的特点,分析了学科评估体系对学术期刊与学科建设学术共同体的重要意义与影响机制。基于对第五轮学科评估体系中与学术期刊相关指标和评估方法内容的研究,从主要功能、学术地位、“中国学术期刊”等维度,阐释了学术期刊对学科建设支撑能力的内涵。最后,提出应通过强化各项功能、提升学科内学术地位、实现所有权完全自主等举措,全面增强学术期刊对学科建设的支撑能力。
- 2022.10.25
Rehman, Hakeem-Ur;万国华; Rafique, Raza,A hybrid approach with step-size aggregation to forecasting hierarchical time series,JOURNAL OF FORECASTING,JUL 2022(Online)
【Abstract】Hierarchical time series arise in various fields such as manufacturing and services when the products or services can be hierarchically structured. "Top-down" and "bottom-up" forecasting approaches are often used for forecasting such hierarchical time series. In this paper, we develop a new hybrid approach (HA) with step-size aggregation for hierarchical time series forecasting. The new approach is a weighted average of the two classical approaches with the weights being optimally chosen for all the series at each level of the hierarchy to minimize the variance of the forecast errors. The independent selection of weights for all the series at each level of the hierarchy makes the HA inconsistent while aggregating suitably across the hierarchy. To address this issue, we introduce a step-size aggregate factor that represents the relationship between forecasts of the two consecutive levels of the hierarchy. The key advantage of the proposed HA is that it captures the structure of the hierarchy inherently due to the combination of the hierarchical approaches instead of independent forecasts of all the series at each level of the hierarchy. We demonstrate the performance of the new approach by applying it to the monthly data of 'Industrial' category of M3-Competition as well as on Pakistan energy consumption data.