基于在线评论数据的产品需求趋势挖掘

随着经济水平的提高和物质生活的丰富，消费者的需求变化也越来越快。能否迎合市场需求的变化是企业产品成功的关键。随着社交媒体的发展，消费者为了分享购物体验发表了许多在线评论信息，其中蕴含着消费者的需求变化。本文在产品特征提取和属性情感分析的基础上，构建了垃圾评论识别模型。然后，利用时间序列分析模型预测下阶段的产品属性关注度和情感计算。最后结合历史数据的变化趋势，分析产品属性的重要性和市场满意情况。利用汽车论坛上的汽车评论数据对本文提出的研究模型进行了验证。研究结果可以为企业制定营销策略以及产品改进与创新提供决策支持。     

Permanently online and permanently connected: Taiwanese university students’ attachment style,mobile phone usage,and well-being

Taiwan has been the top country worldwide in terms of its adoption and use of mobile phones. This study explores the permanently online (PO) and permanently connected (PC) phenomenon in mobile phone use among Taiwanese university students. It seeks to determine whether attachment styles are a distinctive factor that influences PO and PC (POPC) behavior and leads to various levels of well-being. The results of this study provide initial evidence that Taiwanese users highly depend on their mobile phones for PC and PO activities but perceive that being permanently connected causes interpersonal stress. Although the findings showed that all styles were positively associated with PO, only the secure and anxious styles predicted PC. Regarding mobile phone activities, the avoidant attachment style was not associated with any activities, the secure attachment style was positively associated with online and voice communication as well as information-seeking activities, and the anxious attachment style was associated only with voice communication. Furthermore, attachment styles lead to various levels of interpersonal stress through PO and PC behavior. The anxious style interacts with PO on interpersonal stress. This study provides evidence that attachment style is a significant antecedent of POPC and its consequences in mobile phone usage.     

Completing the Circuit: Routine,Reflection, and Ethical Consumption

Efforts to explain why some people incorporate ethical concerns into everyday shopping for food and household goods, while many do not, have so far left significant variation in “ethical consumption” unexplained. Seeking to move beyond explanations that rely mainly on differences in consumers' social class, gender, and political engagement, I draw on concepts associated with “practice theory” to argue that ethical consumption is closely tied to people's willingness and ability to spend time, while shopping, on distinct activities associated with breaking old routines and establishing new ones. The central insight of practice theory is that most consumption is the product of unconscious routine. And it is precisely because consciously departing from routine is, according to my study, a fundamentally time‐consuming process, that lack of time emerges as a crucial obstacle to translating abstract ethical concerns into concrete action as a consumer.     

Market economies and pro-social behavior: Experimental evidence from Central Asia

This study seeks to extend the body of knowledge of pro-social behavior in comparative market settings by reporting on a high-stakes ultimatum game and revelation game experiments in two transition economies: Kazakhstan and Uzbekistan. While controlling for cultural differences and framing effects, we find statistically significant differences in fairness and honesty behavior between the two countries. Specifically, subjects in Uzbekistan (in an earlier stage of transition to a market economy) are fairer and more honest than their later-stage Kazakh counterparts. Our experimental findings have implications for the literature on pro-social behavior and market economies, and more generally, on the transmission process between formal and informal institutions.     

India's demand for international reserve and monetary disequilibrium: Reserve adequacy under floating regime

The main aim of this study is to investigate India's demand for international reserve by focusing on the role of national monetary disequilibrium and to present new benchmarks for assessing the adequacy of international reserves. We assessed India's position in terms of reserve adequacy and found that India is well placed and has sufficient stock of international reserves to meet the minimum adequacy requirements. Also, the results reveal that the central bank is holding substantial excess reserves and the related opportunity cost (1.5% of GDP) appears to be quite considerable. Further, the estimates of reserve demand function suggest that scale of foreign trade, uncertainty and profitability considerations play significant role in determining India's long-term reserve demand policies. More importantly, validating the monetary approach to balance of payment, our results show that national monetary disequilibrium does play a crucial role in short-run reserve movements. An excess of money demand (supply) induces an inflow (outflow) of international reserves with an elasticity of 0.56 which also implies that Reserve Bank of India responds to correct the domestic money market disequilibrium; and did not just leave it completely on the mercy of reserve inflows.     

A Semiparametric Regression Model for Longitudinal Data with Non‐stationary Errors

Motivated by the need to analyze the National Longitudinal Surveys data, we propose a new semiparametric longitudinal mean‐covariance model in which the effects on dependent variable of some explanatory variables are linear and others are non‐linear, while the within‐subject correlations are modelled by a non‐stationary autoregressive error structure. We develop an estimation machinery based on least squares technique by approximating non‐parametric functions via B‐spline expansions and establish the asymptotic normality of parametric estimators as well as the rate of convergence for the non‐parametric estimators. We further advocate a new model selection strategy in the varying‐coefficient model framework, for distinguishing whether a component is significant and subsequently whether it is linear or non‐linear. Besides, the proposed method can also be employed for identifying the true order of lagged terms consistently. Monte Carlo studies are conducted to examine the finite sample performance of our approach, and an application of real data is also illustrated.     

Lawrence R. Klein 1920–2013: Notes on the early years

Klein can well be said to have created the field of macroeconometric modeling almost singlehandedly. His international influence started at an early stage. The article offers scattered archive observations on Klein's early years from undergraduate study to the University of Pennsylvania in 1958. Klein was in 1944 recruited by the Cowles Commission in Chicago to construct the first macroeconomic model in the USA, drawing on the experiences of the interwar modeling work of Jan Tinbergen and the new path-breaking econometric methods developed by Trygve Haavelmo. The first Klein model was taken into use at the end of 1945 to shed light on the prospects for the US economy in the transition from war to peace. After two-three years in Chicago Chicago, Klein traveled for a year in Europe and initiated macroeconometric modeling work in Canada, at the University of Michigan, and at Oxford University. This was only the beginning of the lifelong influence exerted on modelers around the globe. The article pays attention to Klein's relation to Paul Samuelson, Jacob Marschak, Trygve Haavelmo, Ragnar Frisch, and others.     

A Unified Way to Represent and Compute the Cumulative Distribution Function for Noncentral t,F, and χ2

This short article shows an unified approach to representing and computing the cumulative distribution function for noncentral t, F, and χ². Unlike the existing algorithms, which involve different expansion and/or recurrence, the new approach consistently represents all the three noncentral cumulative distribution functions as the integral of the normal cumulative distribution function and χ² density function.     

Asymptotic expaxsioxs for the joint distribution of cirrelated hotellings t2 statlstics under normality

Let T² _i=z′_iS^?1z_i, i==,…k be correlated Hotelling's T² statistics under normality. where z=(z′_i,…,z′_k)′ and nS are independently distributed as N_kp((O,ρ?∑) and Wishart distribution W_p(∑, n), respectively. The purpose of this paper is to study the distribution function F(x₁,…,x_k) of (T² _i,…,T² _k) when n is large. First we derive an asymptotic expansion of the characteristic function of (T² _i,…,T² _k) up to the order n^?2. Next we give asymptotic expansions for (T² _i,…,T² _k) in two cases (i)ρ=I_k and (ii) k=2 by inverting the expanded characteristic function up to the orders n^?2 and n^?1, respectively. Our results can be applied to the distribution function of max (T² _i,…,T² _k) as a special case.     

特低渗透油藏 CO2 驱室内实验研究

针对大庆外围油田特低渗透油藏剩余油潜力大、井网加密效益差、水驱采收率低等问题，提出了特低渗透油藏 CO2驱技术。通过细管实验和天然岩芯 CO2 驱油实验，确定了 CO2 与高台子油田原油的最小混相压力，评价了特低渗透砂岩油藏 CO2 驱油效果。实验结果表明，CO2 驱可以应用于高台子油田，并取得较好的驱油效果。当天然岩芯空气渗透率为0.58 mD 时，在水驱基础上，气驱可以进一步提高采收率 8% 以上，特低渗透油藏实施 CO2 驱油技术是可行的。