The information stated by Public Hospitals to the Central Administration of the Health System, concerning cases of clinical hospitalization, goes through a process of grouping Homogeneous Diagnoses. The “pathological-numeric” codification is a matter of extreme importance for the monitoring...

The paper aims to discuss the concept of truth in its relation with causality. More exactly, the relation of causality between… causality and truth recognition is exposed and debated. The three types of truth are presented and examined in the light of the paper purpose, commenting on...

The paper has as goal to revisit the general concept of causality, with some specifications to the social (especially economic) field. The logical conditions of causality (individual causes as well multiple causes) are proposed and evaluated. Based on causality concept, the correlation notion is...

Rigour versus Relevance impliziert einen Gegensatz, der nicht existiert. Auch die übliche Gleichsetzung von Rigor mit Wissenschaft und Relevanz mit Praxis führt zu falschen Schlüssen. Stattdessen wird gezeigt, dass die Unterscheidung zwischen Rigor und Relevanz inner-halb der Wissenschaft...

We introduce Stochastic Flow Diagrams (SFDs), a new mathematical approach to represent complex dynamic systems into a single weighted digraph. This topological representation provides a way to visualize what otherwise would be a morass of equations in differences. SFDs model the propagation and...

Bid and ask sizes at the top of the order book provide information on short-term price moves. Drawing from classical descriptions of the order book in terms of queues and order-arrival rates (Smith et al., 2003), we consider a diffusion model for the evolution of the best bid/ask queues. We...

In this paper we investigate trading with optimal mean reverting portfolios subject to cardinality constraints. First, we identify the parameters of the underlying VAR(1) model of asset prices and then the quantities of the corresponding Ornstein-Uhlenbeck (OU) process are estimated by pattern...

Intraday volatility and market impact models in volume time are proposed. We build an intraday volatility profile to capture non-stationarity of intraday price returns and utilize a fractional Brownian motion process to measure deviations from square root scaling rule of volatility. <p> We propose...</p>

A large portion of Macroeconomic and Financial research is built upon classical applications of Linear Algebra (such as regression analysis) and Stochastic Calculus (such as valuation models). As a result, most Macroeconomic and Financial research has inherited a focus on geometric locations...

In this paper we consider convex combinations of matrices that arise in the study of distribution problems and analyse the properties of Perron's eigenvalue, and its associated positive eigenvector. We prove that the components in the (normalized) associated positive eigenvector have a monotone...