随机需求下横向并购供应链网络整合优化策略研究

本文从系统优化视角,针对增设集散中心的横向并购供应链网络整合策略,利用变分不等式建立了随机需求下的整合优化模型。以市场链为主线,以供应链网络均衡理论为基 础,构建了以横向并购供应链网络活动总成本最小为目标的数学模型,通过转换成变分不等式采用改进的欧拉算法进行模型求解。通过数值算例进一步说明了模型的适用性和灵活性,得出了增设集散中心的并购整合策略能够降低供应链网络的平均运营成本的结论,通过对比不同市场紧密程度下产生的供应链网络平均成本协同效应,发现随着市场紧密程度的增加其协同效应更明显,为横向并购供应链网络整合优化提供理论依据与方法。     

Crime and punishment: the role of student body characteristics in schools’ disciplinary behaviours

Discretion in schools’ discipline choices can provide an efficient and effective misconduct management structure, but could lead to discipline based on unrelated factors. Consequently, schools’ disciplinary decisions can significantly limit students’ access to education by removing students from familiar learning environments. We investigate schools’ disciplinary decisions for serious misconducts and show that punishments are more severe in schools that do not report misconducts to local law enforcement agencies. Moreover, we show that schools that report fewer misconducts to law enforcement impose more severe punishments when the student body is characterized as having a higher proportion of minority students, lower socioeconomic status students and a higher proportion of students who are below the 15th percentile of standardized test scores. These results suggest that between-school punishment differentials are associated with student body traits.     

Mobility of Top Incomes in Germany

I analyze German top income mobility using micro‐level panel data of personal income tax returns which are highly representative for top income taxpayers for the years 2001–06. Top income mobility is assessed in three dimensions: (i) persistence in top income fractiles and its stability over time, (ii) measures of individual mobility that are not dependent on the fractile size: the degree of mobility between equally sized groups and mobility in ranks, and (iii) mobility's impact on top income shares. Persistence in top income fractiles is comparatively high and fairly stable across the analyzed period. Top income recipients are less prone to downward mobility and see less variation in annual ranks than less rich tax units. Mobility's impact on income concentration is moderate. The top percentile's share is reduced by roughly 5 percent over six years.     

Correcting for the Missing Rich: An Application to Wealth Survey Data

It is a well‐known criticism that if the distribution of wealth is highly concentrated, survey data are hardly reliable when it comes to analyzing the richest parts of society. This paper addresses this criticism by providing a general rationale of the underlying methodological problem as well as by proposing a specific methodological approach tailored to correcting the arising bias. We illustrate the latter approach by using Austrian data from the Household Finance and Consumption Survey. Specifically, we identify suitable parameter combinations by using a series of maximum‐likelihood estimates and appropriate goodness‐of‐fit tests to avoid arbitrariness with respect to the fitting of the Pareto distribution. Our results suggest that the alleged non‐observation bias is considerable, accounting for about one quarter of total net wealth in the case of Austria. The method developed in this paper can easily be applied to other countries where survey data on wealth are available.     

Selection on performance and tracking

Tracking is widely used in secondary schools around the world. Some countries put more emphasis on the use of performance to place students into tracks (e.g. the Netherlands), while in other countries parents have more influence on the track their child will go to (e.g. Germany). This article examines whether selection into tracks based on performance has an effect on the relation between tracking and student performance and educational opportunities. Using data from the Programme for International Student Assessment for around 185 000 students in 31 countries, different estimation models are compared. The results indicate that a highly differentiated system is best for performance when schools always consider prior performance when deciding on student acceptance. In systems with a few tracks, there is no such impact. Equality of opportunity is best provided for in a system with many tracks when schools always consider prior performance.     

Accounting students’ choice of blended learning format and its impact on performance and satisfaction

Using online platforms to deliver educational content, some institutions have developed blended courses that combine the advantages of online instruction with traditional face-to-face (F2F) teaching. This study compares accounting student performance and satisfaction in two blended formats with similar content and design, i.e. F2F+ vs. Online+ courses. It also assesses the characteristics of students who choose the latter option over F2F+ courses. Students in four advanced accounting subjects were surveyed and their course performance was obtained. Results indicate that the main determinants of students’ decision to register for an Online+ course are retaking the course, increased weekly work hours, and belief that this type of blended course facilitates learning. Results show that students in advanced accounting courses with equivalent content and design perform similarly and have the same level of course satisfaction across course delivery formats, as hypothesized under equivalency theory.     

Expected shortfall estimation for apparently infinite-mean models of operational risk

Statistical analyses on actual data depict operational risk as an extremely heavy-tailed phenomenon, able to generate losses so extreme as to suggest the use of infinite-mean models. But no loss can actually destroy more than the entire value of a bank or of a company, and this upper bound should be considered when dealing with tail-risk assessment. Introducing what we call the dual distribution, we show how to deal with heavy-tailed phenomena with a remote yet finite upper bound. We provide methods to compute relevant tail quantities such as the Expected Shortfall, which is not available under infinite-mean models, allowing adequate provisioning and capital allocation. This also permits a measurement of fragility. The main difference between our approach and a simple truncation is in the smoothness of the transformation between the original and the dual distribution. Our methodology is useful with apparently infinite-mean phenomena, as in the case of operational risk, but it can be applied in all those situations involving extreme fat tails and bounded support.     

Price Rigidity in Turkey: Evidence from Micro Data

In this study we investigate the duration of consumer price spells and price change patterns for Turkey by employing a comprehensive micro price data covering around 6,000 items over four years. In detail, we analyze how long typical price spell lasts and we investigate the size, frequency, distribution and synchronization of price changes. Compared to advanced economies, a higher frequency of price changes is estimated. Findings suggest substantial heterogeneity among sub-groups in terms of frequency and synchronization indicators. The mixed evidence of both state and time-dependent pricing is also relevant for Turkey, an emerging market economy.     

Random matrix application to correlations amongst the volatility of assets

In this paper, we apply tools from random matrix theory (RMT) to estimates of correlations across the volatility of various assets in the S&P 500. The volatility inputs are estimated by modelling price fluctuations as a GARCH(1,1) process. The corresponding volatility correlation matrix is then constructed. It is found that the distribution of a significant number of eigenvalues of the volatility correlation matrix matches with the analytical result from RMT. Furthermore, the empirical estimates of short- and long-range correlations amongst eigenvalues, which are within RMT bounds, match with the analytical results for the Gaussian Orthogonal ensemble of RMT. To understand the information content of the largest eigenvectors, we estimate the contribution of the Global Industry Classification Standard industry groups to each eigenvector. In comparison with eigenvectors of correlation matrix for price fluctuations, only few of the largest eigenvectors of the volatility correlation matrix are dominated by a single industry group. We also study correlations between ‘volatility returns’ and log-volatility to find similar results.