Big Data and Dietary Trend: The Case of Avocado Imports in China

ABSTRACT

The advancement of data science and technology presents a unique opportunity to understand rapidly evolving dietary trend around the world. In this case study, we show that the Baidu index, a measurement of the intensity of user searches for specific words, helps explain and forecast the growth of avocado imports in China. Specifically, we find that China’s avocado imports rise by 8% in response to a 10% increase in the Baidu index. Furthermore, the inclusion of the Baidu index in a standard demand model reduces the prediction error by 2.7%.     

Marketing Innovation in Rural Small Food Industries in Iran

Marketing innovation is essential for small industries to transform products into profit; therefore, understanding its nature and determinants is of utmost importance. This study aimed at understanding marketing innovation and its determinants in the 60 small food industries in the rural areas of Tehran province, Iran. Using a census sampling method, 111 managers of these firms were interviewed. Results showed that the firms’ performance in marketing innovation is generally weak, and a higher level of radical innovation in marketing is perceived compared to the incremental innovation. Also, a cause-and-effect relationship exists between both product and organizational innovations and marketing innovation. Furthermore, while incremental marketing innovation was negatively influenced by formal R&D unit, product diversification, and the manager’s years of experience, radical marketing innovation was affected by the capacity of production, product diversification, and managers’ age and education. The study concluded that in order to boost marketing innovation, innovation should be made also in products and organization. In addition, in order to facilitate the process of marketing innovation, practical and updated training for managers encouraging incremental innovation in marketing, product diversification, and improving R&D activities in the studied firms should be regarded.     

RANDOM COEFFICIENT MODELS: THEORY AND APPLICATIONS

Abstract. This paper provides an overview of the rationale behind, and the implementation, and uses of, the random coefficient approach to econometric modelling. A simple random coefficient model is presented, and methods for estimating, testing, and validating such a model are described. A more general model is then presented. The general model is shown to include several fixed-coefficient models as special cases and can be estimated incorporating a variety of judgements concerning simplification. Finally, the paper reviews recent applications of random coefficient estimation.     

贴现评价指标在互斥项目评估中的矛盾协调研究

净现值、内部收益率和盈利指数是投资项目评估中的三种贴现指标。但三者在互斥项目评估中有时会出现矛盾冲突。分析了三种贴现指标在互斥项目评估中出现矛盾冲突的原因,并在此基础上提出了关于协调此类矛盾冲突的方法。     

转轨国家经济绩效的动态比较分析

作为经济转轨的两种方式,渐进式改革和激进式改革孰优孰劣,一直是转轨经济学理论争论的焦点之一,围绕此形成了两种截然不同的学术观点。那么,到底哪种观点更能得到实践的支持,针对该研究问题,以24个转轨国家作为研究样本,运用整体比较和分阶段比较的研究方法,从整体上和分阶段两个方面对渐进式改革的国家和激进式改革的国家的经济绩效进行评价和比较,研究结论基本支持渐进式改革方式从整体上更有利于经济发展的观点。但是作为对现有研究的补充和发展,发现个别激进式改革的苏东国家在转轨后的第四个阶段其经济绩效水平要高于渐进式改革的国家。     

从渐进型创新到突破型创新——温州技术创新转型研究

改革开放以来,温州模式在促进当地经济发展中的表现举世瞩目,温州的民营企业依赖渐进型创新逐步降低生产成本和提高产品质量,取得了较大的竞争优势。但是,随着渐进型创新机会被逐渐耗尽,温州经济面临从依赖渐进型创新到依赖突破型创新的转型问题。文章以温州为例,分析了高度分工的企业集群生产模式和地方政府的自由放任政策对技术创新转型的影响。     

Sparse estimation of dynamic principal components for forecasting high-dimensional time series

We present the sparse estimation of one-sided dynamic principal components (ODPCs) to forecast high-dimensional time series. The forecast can be made directly with the ODPCs or by using them as estimates of the factors in a generalized dynamic factor model. It is shown that a large reduction in the number of parameters estimated for the ODPCs can be achieved without affecting their forecasting performance.     

基于材料性能劣化的RC框架结构抗震性能评估及易损性分析

为了提高钢筋混凝土(reinforced concrete, RC)框架结构的使用寿命,明晰长期服役后的材料劣化对结构抗震性能和易损性的影响程度,建立了考虑材料性能劣化的RC框架结构的有限元分析模型。选取材料性能未劣化(100%)以及分别劣化至90%,80%和70%时的4种工况(依次表示为flsc-100,flsc-90,flsc-80和flsc-70)进行抗震性能评估,同时绘制地震易损性曲线,并分析其在不同地震强度作用下的易损性。结果表明：1)随着材料劣化程度的加剧,RC框架结构在不同地震波下的抗震性能明显降低。罕遇地震作用下,flsc-70的层间位移角比flsc-100增大了80%;2)随着结构刚度及承载力的降低,RC框架结构在不同破坏状态下的超越概率均有显著提升。罕遇地震作用下,flsc-90,flsc-80和flsc-70发生严重破坏的超越概率比flsc-100分别增大了75%,300%和975%。因此,在既有结构抗震性能评估中考虑材料性能劣化的影响十分必要。研究结果可以帮助预测材料性能劣化的RC框架结构在地震发生时的损伤程度,为结构的加固及修复提供参考依据。     

基于CatBoost的护士离职预测研究

针对传统的离职预测算法应用于现实中高维度小样本不平衡数据集时存在准确度低、易过拟合、鲁棒性差等问题,应用梯度增强集成分类器CatBoost算法,进行类别型特征处理,利用BOHB(Bayesian Optimization and Hyperband)寻找最优参数,结合交叉验证对模型分类性能进行评估,建立分类模型并对护士离职情况进行预测。该算法采用高维小样本不平衡特征的上海部分公立医院的护士离职数据集,并与XGBoost、随机森林、支持向量机进行对比。实验结果表明,该算法准确度高,鲁棒性强,能够有效地对护士离职进行预测。     

互补资产对企业技术创新的影响——基于中国上市公司的实证研究

本文在文献回顾的基础上,分析了互补资产对渐进性和突破性技术创新的影响,并通过中国医药制造、电子信息和电气设备制造等三个行业103家上市公司2004～2008年的数据,对二者的关系进行了实证分析。本文的主要发现和结论是:企业互补资产的积累有利于渐进性技术创新,但不利于突破性技术创新;不同类的互补资产对突破性创新的影响有所不同,互补生产制造和人力资产不利于突破性技术创新,而互补营销资产的积累有利于突破性技术创新。