Applying free random variables to random matrix analysis of financial data. Part I: The Gaussian case

We apply the concept of free random variables to doubly correlated (Gaussian) Wishart random matrix models, appearing, for example, in a multivariate analysis of financial time series, and displaying both inter-asset cross-covariances and temporal auto-covariances. We give a comprehensive introduction to the rich financial reality behind such models. We explain in an elementary way the main techniques of free random variables calculus, with a view to promoting them in the quantitative finance community. We apply our findings to tackle several financially relevant problems, such as a universe of assets displaying exponentially decaying temporal covariances, or the exponentially weighted moving average, both with an arbitrary structure of cross-covariances.     

After retrotopia? The future of organizing and the thought of Zygmunt Bauman

The main body of work of Zygmunt Bauman concerns his home discipline of sociology, but his insights have been influential also in the field of organization studies. In this text, we provide an overview of the extent of this influence, providing some additional context for positioning the other contributions to this special section. Afterwards, we explore in more detail two notions central for Bauman’s late thought: that of liquidity and retrotopia. The former constitutes the root metaphor for theorizing the current global predicament. In this text, we analyse how two modes of interpreting it, using the assumptions behind Kurt Lewin’s CATS model and the alchemical tradition underpinning Carl Gustav Jung’s conception of archetypes respectively, can help us theorize the alternative modes of organizing and managing encountered in a study of contemporary alternative organizations.These insights form the starting point for our second goal: to explore Bauman’s notion of retrotopia as a potentially fruitful starting point for discussing both the deficiencies of current visions of our future society, and the possibilities and vicissitudes of developing new forms of organizing and managing. Such new forms, both as practice and as theoretical constructs, are urgently needed if we are to face the numerous, and potentially catastrophic global challenges facing our society today.     

Demographic impacts in central and eastern European countries

All countries undergoing socioeconomic transformation in the central, eastern, and southeastern parts of Europe, regardless of the progress made in systemic transformation, have witnessed significant changes in their population. This paper presents some of these demographic changes and considers the dynamics produced by a drop in reproduction rates and the declining frequency of marriages. The intensity of these changes tended to vary. All of the countries, with the exception of Albania, are characterized by low birth rates approaching nominally the level of death rates. Infant mortality rates in the majority of the countries were relatively high at the beginning of the 1990s compared with their minimum.     

An Alternative for Time Series Models

Two methods for construction of new stochastic processes with discrete time are presented. One of the methods employs as the defining tool “triangular （more specifically ＇pseudoaffine＇） transformations” which are extended from the Euclidean R^n to infinite dimension space. They transform any well-known discrete time stochastic process into the constructed one. The other more flexible method is the “method of parameter dependence”, extended to infinite dimension. Properties of the obtained stochastic processes （by either method） indicate the possibility to apply them for financial analysis, as an alternative for the classical time series models. The advantage of the presented models over the existing ones first of all relies on expected better accuracy. This follows from the fact that the typically held assumption on Markovianity in the existing models can easily be relaxed. The defined processes may incorporate a quite long memory including, among others, the k-Markovian cases for k _〉 2. Regardless the non-Markovianity of the models they still are tractable in an analytical or numerical way. The stochastic processes defined in this paper provide more flexible and more general tools than the existing time series models for modeling financial problems. Among others, they make it possible to incorporate the influence of environmental （explanatory） random variables on the underlying stochastic models＇ behavior. These additional features turn out to be describable by the method of parameter dependence. Some suggestions for an associated preliminary statistical analysis are included.     

Disability and Discrimination - a UK Perspective

"Discrimination on the grounds of disability is seldom malicious, but stems more from a lack of understanding." A disabled businessman explores the need for businesses to cultivate and implement greater disability awareness. After graduating in engineering, he gained his MBA from London Business School in 1992. He now works as a consultant, capitalising on his background in business management and his personal experience of disability to assist clients in developing anti-discriminatory policies and practice.     

Inflation and price setting in a natural experiment

We analyze the behavior of price setters in Poland during the transition from a planned to a market economy, using a large disaggregated data set. The size and frequency of price changes, as well as relative price variability, all increase as inflation rises. The effect of expected inflation on relative price variability is much stronger than the effect of unexpected inflation. Despite the unusual economic environment, the results are qualitatively identical, and quantitatively stronger, than those in Lach and Tsiddon [1992. Journal of Political Economy 100, 349-389].     

Dividend-Driven Trading Strategies: Evidence from the Warsaw Stock Exchange

This study presents an analysis of dividend-driven trading strategies based on dividend yield growth effects in the Polish stock market in the years 1994–2004. Results indicate that the dividend yield growth portfolios were capable of beating the market in the entire sample period. Their performance, however, was not consistent over time and the highest returns were obtained during final years. Empirical findings based on the analysis of different types of portfolios demonstrate the importance of dividends as a source of significant fundamental information items from stock market companies. At the same time, they show that a dividend investment strategy for the Polish stock market is most successful when the selection of stocks for the dividend yield growth portfolios is subject to further restrictions, most notably concerning company size.