A Geometrical Interpretation of Collinearity: A Natural Way to Justify Ridge Regression and Its Anomalies

Justifying ridge regression from a geometrical perspective is one of the main contributions of this paper. To the best of our knowledge, this question has not been treated previously. This paper shows that ridge regression is a particular case of raising procedures that provide greater flexibility by transforming the matrix X associated with the model. Thus, raising procedures, based on a geometrical idea of the vectorial space associated with the columns of matrix X , lead naturally to ridge regression and justify the presence of the well-known constant k on the main diagonal of matrix X ^′ X . This paper also analyses and compares different alternatives to raising with respect to collinearity mitigation. The results are illustrated with an empirical application.     

Stock markets fragmentation,volatility and final investors

The 2000s in equity markets are marked by two major regulatory shocks: RegNMS in the United States, and MiFID in the European Union. Simultaneously, there is a massive increase in the proportion of high-frequency trading, and market orders volume. However, trading volumes do not significantly increase. We propose a theoretical model describing the effects of stock markets fragmentation on two types of investors optimization problems: “intermediary” high-frequency and “final” investors. Volatility has a permanent and a transitory component, whose weights depend on market fragmentation via the share of non-marketable orders of intermediary investors. The trading volume of final investors depends on market fragmentation both directly via transaction costs, and indirectly via total volatility. Finally a shock in fragmentation may lead to a decrease in trading volume, enhanced in the case of an equity markets crisis by a rise in the components of volatility.     

Aggregation of Directional Distance Functions and Industrial Efficiency

Three main objectives are pursued in this paper. First, we intend to analyze the aggregation problem of directional distance functions from a constructive viewpoint. We provide necessary and sufficient conditions concerning the structural properties of the production technology and of the nature of groups of firms. Indeed, exact additive aggregation holds for a linear technology and for a direction solely defined in the output space. Second, since these conditions are somewhat restrictive, we are interested in providing a measure for the aggregation bias through the relationship between industrial and structural technical efficiency. Finally, we show that this aggregation bias is a lower bound for industrial allocative efficiency.     

How resilient is La Réunion in terms of international tourism attractiveness: an assessment from unit root tests with structural breaks from 1981-2015

Even if local policymakers increasingly claim that tourism is one of the key factors of future economic development for the French small island La Réunion, international tourist arrivals are observed to be locked in a stagnation phase since the beginning of the 2000s. Starting from this stylized fact, this article aims to study if this phenomenon results from major external events hurting this economy regularly. Next, by using univariate unit root procedures with structural breaks, we test for evidence of permanent or transitory effects of external shocks on international tourist inflows (total, by source markets, and by category) over the period 1981–2015. Finally, the empirical analysis allows us to reject the null of a unit root. Then, stagnation of tourism arrivals to La Réunion is not due to exogenous shocks but probably results from endogenous impediments within the domestic tourism industry and unsuitable public policies.     

Media visibility and corporate social responsibility investment evidence in Spain

Despite the extensive research in both the determinants and the results of corporate social responsibility (CSR), relatively few studies have considered extra-legal institutions as potential determinants of CSR. Our work fills this gap by looking at how media attention affects CSR over a long-term period in a continental European setting. Our results show that media coverage positively affects CSR. Additional scrutiny triggered by media coverage encourages dominant owners to signal their commitment to limiting self-dealing transactions and their orientation toward stakeholders' needs through CSR investments. Additionally, our results reveal that this signaling device offers greater benefits and lower costs in firms where controlling owners show a voting-cash flow wedge. Our results are relevant to different actors such as investors, auditors, and policy makers as they provide solid evidence that media coverage is an important driver of CSR orientation in a continental European setting.     

Using templates and linguistic patterns to define process performance indicators

Process performance management (PPM) aims at measuring, monitoring and analysing the performance of business processes (BPs), in order to check the achievement of strategic and operational goals and to support decision-making for their optimisation. PPM is based on process performance indicators (PPIs), so having an appropriate definition of them is crucial. One of the main problems of PPIs definition is to express them in an unambiguous, complete, understandable, traceable and verifiable manner. In practice, PPIs are defined informally – usually in ad hoc, natural language, with its well-known problems – or they are defined from an implementation perspective, hardly understandable to non-technical people. In order to solve this problem, in this article we propose a novel approach to improve the definition of PPIs using templates and linguistic patterns. This approach promotes reuse, reduces both ambiguities and missing information, is understandable to all stakeholders and maintains traceability with the process model. Furthermore, it enables the automated processing of PPI definitions by its straightforward translation into the PPINOT metamodel, allowing the gathering of the required information for their computation as well as the analysis of the relationships between them and with BP elements.     

Estimation of Asymmetric Stochastic Volatility Models: Application to Daily Average Prices of Energy Products

Energy supply and demand, and as a consequence energy prices, are likely to represent one of the biggest challenges of the 21st century. Commodity markets exhibit increased volatility when there is little or no underutilized supply capability to meet natural fluctuations in demand. In the case of energy markets, the large capital requirements and significant lead times associated with energy production and delivery make them more susceptible to the imbalances in supply capability and demand. Energy price volatility has destructive impact on market agents, and this impact is intensified when the prices exhibit asymmetric volatility. This article pursues two aspects of the issue. First we consider general aspects, especially the asymmetric pattern of volatility of daily returns of different types of energy products. Then, we analyze the behaviour of daily returns by using traditional models of volatility that include AGARCH, TGARCH, EGARCH, and ARSV strategies, as well as a threshold asymmetric autoregressive stochastic volatility (TA-ARSV) model that we propose. The energy products considered in this analysis are probably the most relevant energy products for the economic activity of the nations and the economic relations between countries: Crude Oil (OPEC reference basket and London Brent index), Gasoline, Natural Gas, Butane, and Propane. We use spot prices and the time reference ranges from 1986–1993 to 2009 depending on the product.     

Content analysis research method with Nvivo-6 software in a PhD thesis: an approach to the long-term psychological effects on Chilean ex-prisoners survivors of experiences of torture and imprisonment

The aim of this paper is to review the usefulness of the software CAQDAS QSR—Nvivo-6 in a PhD. Thesis, which consisted of finding the long-term psychological effects of experiences of imprisonment and torture for political reasons in their Chilean survivors. For this research, it was created and administered an in-depth interview to 60 survivors, from which outcome was 9900 paragraphs, coded into 784 categories. The software QSR Nvivo-6 threw a report of frequencies, which were compared quantitatively using Pearson’s χ ² square test and cluster analysis. We conclude that the software facilitates the development of qualitative thematic content analysis, simplifying the coding, analysis and display of data. In Addition, it is very useful when working with large quantities of information, promoting the reliability and validity of studies. However, other aspects are also required to ensure the rigor of a qualitative study.     

A linear approximation to the power function of a test

In this paper we obtain a linear approximation to the power function of a test that is very accurate for small sample sizes. This is especially useful for robust tests where not many power functions are available. The approximation is based on the von Mises expansion of the tail probability functional and on the Tail Area Influence Function (TAIF). The goals of the paper are, first to extend the definition of the TAIF to the case of non identically distributed random variables, defining the Partial Tail Area Influence Functions and the Vectorial Tail Area Influence Function; second, to obtain exact expressions for computing these new influence functions; and, finally, to find accurate approximations to the power function, that can be used in the case of non identically distributed random variables. We include some examples of the application of this linear approximation to tests that involve the Huber statistic and also saddlepoint tests, so proving that the approximations apply not only to simple problems but also to complex ones.