The Gini index: A proposal for revision

The Gini index is widely used in statistics for the study of equity in the distribution of a variable. However, its definition has several formulations and its use sometimes has hidden problems that can lead to incorrect conclusions. That is the reason why it is necessary to make some remarks this regard and even formulate some proposals to clarify some errors on its definition and use. We present an alternative to solve this error in one of the most popular formulas of the Gini index.

¿Se puede especular con conciencia? La evolución histórica de la inversión socialmente responsable

“Do no harm”. This is the core of traditional investment based on religion and, to some degree, the central concept of socially responsible investment (SRI): avoiding industries that conflict with moral values. As a result of social, ethical and environmental deficiencies arose throughout history; Financial Responsibility has led to this new type of investment as a driver of change in the management of companies and the society. Social and financial awareness worldwide and the different national legislations have led to various SRI practices. The aim of this work is building, from a historical perspective, the development of SRI in Europe and in Spain and of its main financial instrument, the Socially Responsible Investment Funds.

Inteligencia artificial como herramienta de análisis en gestión value

Although it is assumed that the securities with lower ratios are cheaper and should perform better than the market, "value investment" has not being able to beat the market. In this study, we try to identify if artificial intelligence can be a useful tool in "value investment" and can identify which securities or portfolios are going to beat the market. For this purpose, different trainings have been carried out on an artificial intelligence model that uses ratios as predictors, while the target variable takes the values "beat /don't beat" the market. The results obtained for the Spanish and American market show that the predictive capacity of the model exceeds 60% and that a portfolio designed by an expert system based on artificial intelligence is able of beating Ibex 35. Therefore, artificial intelligence is a useful tool for managing assets with a value profile, either as a tool to aid the analyst's research or as the engine of an expert system that designs portfolios with the aim of beating the market.

SCR en el riesgo de suscripción del seguro de vida: mortalidad, longevidad y reaseguro

The aim of this work is to propose an internal model based on the Monte Carlo’s simulation method, for the calculation of the solvency capital requirement of the subscription of life’s risk, of an insurances company that presents two risks, the survival and mortality ones. Unlike the standard model, the aggregation of these two risks will carry out without knowing the correlation matrixes. Afterwards, the effect that the different modalities of reinsurance have in the solvency capital requirement will be analyzed. The modalities of reinsurance object of analysis are the quota share, the surplus and the stop-loss.

New indexes for measuring electoral disproportionality

The number of representatives obtained by each political party in an electoral process must be a whole number. So, the percentage of votes for each party usually differs from the corresponding percentage of seats, forcing a certain unavoidable disproportionality. On the other hand, different elements of the electoral system (constituencies, thresholds, etc.) may produce some avoidable disproportionality. Those indexes traditionally used to analyse disproportionality take into account an unreachable exact proportionality as a reference. Instead, our more realistic approach quantifies distortions from a specific allotment, namely the seat distribution obtained when applying a proportional method to the total votes (that is, as if it were a unique constituency, without electoral thresholds or incentives to the winning party). Hence, we measure the avoidable disproportionality associated with such method. Unlike traditional indexes, we propose indexes associated with proportional allotment methods that can be zero in real situations. They are simple to calculate and allow us to decipher the number of seats assigned beyond the inevitable disproportionality which arises from the constraint of whole numbers. We are particularly interested in the indexes associated with Jefferson and Webster methods, which are compared to Gallagher, Loosemore-Hanby and Sainte-Laguë indexes for the results of 55 elections held in several countries.

Cálculo de los niveles del stock disponible al inicio del ciclo mediante un formalismo fuzzy

Accurate inventory management is essential for the proper functioning of companies. Following a continuous review inventory policy under lost sales assumption, this paper proposes the estimation of on-hand stock levels at order delivery using fuzzy techniques that seek to obtain a reduction in computational costs and include demand uncertainty in the model. To this end, after describing the theoretical formalization, we design an experiment that shows the applicability and potentially of the proposed fuzzy method.

El efecto del tamaño sobre la rentabilidad de las empresas comerciales uruguayas

The objective of this work is to analyze the link between the size and financial economic performance of the Uruguayan trading sector, within the framework of the international contributions of the firm's theory and also considering local background. The database to be used consists of the annual financial statements presented to the General Tax Directorate (DGI) by trading companies belonging to the Special Control Group of Companies (CEDE) and Large Taxpayers of Uruguay in the period 2010-2016. The size dimension of these companies is included in the study through the variables representative of their sales volume or their level of assets. The size of the financial economic performance of the companies is measured through the ROA (Return On Assets) and ROE (Return on Equity) indicators. The methodological strategy consists of the application of dynamic clustering and linear regression tools. The results of the study allow us to characterize the structure of the determinants of the economic and financial performance of commercial companies and their dynamic evolution in the period of analysis, shedding light on the validation of the theories that link it with the size of the companies in Uruguay.