基于情感分析混合模型的用户评论主题分析 ——以vivo手机为例

为了帮助商家了解用户需求和产品问题,进一步提升产品和服务质量,对vivo手机评论数据进行基于关键词的词云图分析、社会语义网络分析、舆情时间序列可视化分析,挖掘用户关注焦点与手机特征的内在联系和用户情感倾向趋势;然后对评论数据进行基于LDA的主题特征分析,继而提出一种基于Word2vec和SVM、LDA的混合算法模型,挖掘用户正向和负向情感评论的潜在主题,得到不同情感倾向下用户对vivo手机不同方面的反映情况。分析结果表明,基于混合算法的挖掘结果比基于关键词的可视化分析、基于LDA的主题分析更清晰,更具准确性,为商家提供的建议更有意义。     

Mutual monitoring and corporate governance

Mutual monitoring in a well-structured authority system can mitigate the agency problem. I empirically examine whether the number two executive in a firm, if given authority, incentive, and channels for communication and influence, is able to monitor and constrain the potentially self-interested CEO. I find strong evidence that: (1) measures of the presence and extent of mutual monitoring from the No. 2 executive are positively related to future firm value (Tobin’s Q); (2) the beneficial effect is more pronounced for firms with stronger incentives for the No. 2 to monitor and with higher information asymmetry between the boards and the CEOs; and (3) mutual monitoring is a substitute for other governance mechanisms. The results suggest that mutual monitoring provides important checks and balances on CEO power.     

B2C模式下转换成本对网上顾客忠诚影响实证研究

基于转换成本的视角,本文构建了一个影响网上顾客忠诚的概念模型。实证研究表明,网络程序转换成本、网络财务转换成本与网络关系转换成本这三种网络转换成本均正向影响网上顾客的行为忠诚度,只有网络财务转换成本和网络关系转换成本正向影响网上顾客的态度忠诚度。三种类型转换成本的构成因子对顾客的态度忠诚和行为忠诚的影响机理是不同的:利益损失成本、个人关系损失成本和品牌关系损失成本起着正向影响顾客态度忠诚的作用;评估成本、学习成本、利益损失成本和品牌关系损失成本起着正向影响顾客行为忠诚的作用。     

Multi-scale tests for serial correlation

This paper introduces a new family of portmanteau tests for serial correlation. Using the wavelet transform, we decompose the variance of the underlying process into the variance of its low frequency and of its high frequency components and we design a variance ratio test of no serial correlation in the presence of dependence. Such decomposition can be carried out iteratively, each wavelet filter leading to a rich family of tests whose joint limiting null distribution is a multivariate normal. We illustrate the size and power properties of the proposed tests through Monte Carlo simulations.     

Bailout uncertainty in a microfounded general equilibrium model of the financial system

This paper develops a micro-founded general equilibrium model of the financial system composed of ultimate borrowers, ultimate lenders and financial intermediaries. The model is used to investigate the impact of uncertainty about the likelihood of governmental bailouts on leverage, interest rates, the volume of defaults and the real economy. The distinction between risk and uncertainty is implemented by applying the multiple priors framework to beliefs about the probability of bailout.Results of the analysis include: (i) An unanticipated increase in bailout uncertainty raises interest rates, the volume of defaults in both the real and financial sectors and may lead to a total drying up of credit markets. (ii) Lower exante bailout uncertainty is conducive to higher leverage, which in turn raises moral hazard and makes the economy more vulnerable to expost increases in bailout uncertainty. (iii) Bailout uncertainty affects the likelihood of bubbles, the amplitude of booms and busts as well as the banking and the credit spreads. (iv) Higher bailout uncertainty is associated with higher returns’ variability in diversified portfolios and higher systemic risks, (v) Pre-crisis expansionary monetary policy reinforces those effects by inducing higher aggregate leverage levels. (vi) The larger the change in bailout uncertainty and the change in aversion to this uncertainty, the stronger the pre-crisis buildup and the deeper the ensuing crisis.A central policy implication of the analysis is that the vaguest is bailout policy prior to a crisis, the lower is the magnitude of investments destroyed or missed due to errors in evaluating bailout and other intervention policies. On the other hand, the clearer is bailout policy upon the eruption of a crisis, the smaller the contraction of credit and the destruction of investment activity.     

Experience,Learning, and Returns to Scale

The experience curve is a tool for forecasting future decreases in average cost as a function of cumulative output/volume. The extent of an experience effect has profound implications for both pricing strategy and the focus on market share as a managerial objective. At the same time, the underlying sources of the experience effect are not well understood. This article demonstrates that, as commonly measured, experience effects are aggregated with the effects of increasing returns to scale. This implies that standard experience curve estimates are misspecified because they suffer from an omitted variable bias. Strategic implications of the experience‐scale link are discussed.     

The eruption of Airbnb in tourist cities: Comparing spatial patterns of hotels and peer-to-peer accommodation in Barcelona

In recent years, what has become known as collaborative consumption has undergone rapid expansion through peer-to-peer (P2P) platforms. In the field of tourism, a particularly notable example is that of Airbnb. This article analyses the spatial patterns of Airbnb in Barcelona and compares them with hotels and sightseeing spots. New sources of data, such as Airbnb listings and geolocated photographs are used. Analysis of bivariate spatial autocorrelation reveals a close spatial relationship between Airbnb and hotels, with a marked centre-periphery pattern, although Airbnb predominates around the city's main hotel axis and hotels predominate in some peripheral areas of the city. Another interesting finding is that Airbnb capitalises more on the advantages of proximity to the city's main tourist attractions than does the hotel sector. Multiple regression analysis shows that the factors explaining location are also different for hotels and Airbnb. Finally, it was possible to detect those parts of the city that have seen the greatest increase in pressure from tourism related to Airbnb's recent expansion.     

B2C电子零售商的业务模式影响因素

互联网经济的飞速发展,使得独立电子零售商的业务模式发生了较大的变化,B2C电子零售商的发展变化尤为明显,由自营销售式为主的独立电商逐渐呈现出自营销售与平台销售并存的方式,且平台销售的份额也在不断增长。本文主要就B2C电商选择平台销售还是自营销售模式提出一些观点,主要分析的是B2C电商在选择其业务模式时考虑的影响因素。     

SVHC第23批新增4项物质测试方法研究

本文建立了同时测定欧盟高关注物质(SVHC)第23批新增的4种物质[1-乙烯基咪唑、-甲基咪唑、4-羟基苯甲酸丁酯、双(乙酰丙酮酸)二丁基锡的气相色谱质谱联用仪(GC-MS)]的检测方法。将样品用二氯甲烷超声后,采用选择离子监控模式(SIM)进行分析样品中的待测物。实验结果表明,4种物质在50 mg/L范围内线性关系良好,线性相关系数为0.995以上;样品加标回收率为94%110%,相对标准偏差(RSD)小于7%;方法检出限分别为2 mg/kg、10mg/kg、0.8 mg/kg、0.6 mg/kg,解决了欧盟新增加的4种SVHC测试问题。     

Comparative persistence and adherence with newer anti-hyperglycemic agents to treat patients with type 2 diabetes in the United States

Objectives: Non-adherence and non-persistence to anti-hyperglycemic agents are associated with worse clinical and economic outcomes in patients with type 2 diabetes. This study evaluated treatment persistence and adherence across newer anti-hyperglycemic agents (canagliflozin, dapagliflozin, sitagliptin, saxagliptin, linagliptin, liraglutide, or exenatide).

Methods: This retrospective cohort study of Truven Health Analytics Marketscan databases included adult patients with type 2 diabetes whose first pharmacy claim for a newer anti-hyperglycemic agent was between February 1, 2014 and July 31, 2014. Treatment persistence and adherence were assessed for 12 months after the first claim (post-index). Persistence was defined as no gap ≥90 days between the end of one pharmacy claim and the start of the next pharmacy claim post-index. Adherence used two definitions: proportion of days covered (PDC) and medication possession ratio (MPR). Multivariable analyses of non-persistence (hazard ratios) and adherence (odds ratios) were adjusted for baseline demographics, drug cost, clinical characteristics, and other anti-hyperglycemic agents.

Results: A total of 11,961 patients met all study selection criteria. Persistence rates at 12 months were significantly greater (p?p?=?0.83; PDC?=?0.79) and canagliflozin 300?mg (MPR?=?0.92; PDC?=?0.81) were greater than for the other index anti-hyperglycemic agents (MPR?=?0.33–0.75; PDC?=?0.33–0.72). Consistent results for treatment persistence and adherence were observed in multivariable analyses that were adjusted baseline characteristics.

Conclusions: Canagliflozin was associated with better treatment persistence and treatment adherence compared with other anti-hyperglycemic agents in real-world settings.