7,086 research outputs found
A link between Kendall's tau, the length measure and the surface of bivariate copulas, and a consequence to copulas with self-similar support
Working with shuffles we establish a close link between Kendall's tau, the
so-called length measure, and the surface area of bivariate copulas and derive
some consequences. While it is well-known that Spearman's rho of a bivariate
copula A is a rescaled version of the volume of the area under the graph of A,
in this contribution we show that the other famous concordance measure,
Kendall's tau, allows for a simple geometric interpretation as well - it is
inextricably linked to the surface area of A.Comment: 12 pages, 3 figure
Exploring the neural correlates of e-Assurance and multi-faced risk in e-Commerce
El comercio electrónico ha permitido a multitud de pequeñas empresas exponer sus productos y aumentar su público objetivo potencial. Pese a la relativa facilidad de introducirse en este mercado, la mayor dificultad estriba en eliminar las barreras que limitan a los consumidores comprar online. Una de las vías que poseen mayor potencial para aumentar la confianza online y reducir el riesgo percibido es dotar a su web de señales de confianza, entre las que destacan los certificados externos, ratings de consumidores y políticas de privacidad. Este estudio precisamente usa una técnica neurocientífica (resonancia magnética funcional) junto a cuestionarios con el propósito de esclarecer objetivamente el procesamiento neurológico de esas tres señales de seguridad online. Además, usando estas nuevas herramientas, pretende dilucidar la debatida dimensionalidad del riesgo percibido. Los resultados aconsejarán a comercios online la señal más útil a incluir en sus webs y se concretarán las dimensiones del riesgo percibido.E-commerce has allowed many small firms sell their products and broaden their target. Despite the relative ease in which vendors enter this marketplace, the strongest difficulty is to decrease barriers which discourage online purchases. One of the most useful ways to increase consumer online trust and reduce perceived risk is creating trust mechanisms in web sites, such as seals of approval, consumer ratings and privacy policies. Specifically, this study applies a neuroscientific tool (functional magnetic resonance imaging- fMRI-) together with questionnaires with the aim to clear up the neural processing of those trust signals (e-assurances). Furthermore, using fMRI, we explore the “under-debated” dimensionality of perceived risk. The findings will advise online retailers with the most useful e-assurance to include in their websites as well as will specify the dimensions of perceived risk
Evolution towards a Sustainable Public Transport in the City of Madrid
This chapter is a vision of the path followed by EMT of Madrid, during 25 years, towards the sustainability, efficiency, and contribution to the air quality in the city, starting from a diesel fleet, until getting a fleet 100% of clean vehicles, mostly GNC, which is already a reality. It shows the evolution and the use, from the practical perspective of an operator, of all the technologies available at each moment (biodiesel, bioethanol, hydrogen, electricity, natural gas, hybridization, dualisation, start-stop, catalysis, etc.) in Madrid, in a fleet of more than 2000 buses, more than 200 lines, and more than 400 million passengers per year, which makes this case an international benchmark. In addition, EMT is currently at the end of the transition to gas vehicles (CNG) and the implementation of urban electric mobility from the double perspective of the mobile material and the associated infrastructure needed, an essential case study towards sustainable public transport
El convento dominico de Nuestra Señora de Las Caldas de Besaya (Cantabria) y la arquitectura religiosa del foco vallisoletano
En el Archivo de la Real Chancillería de Valladolid se conserva una traza del convento de Nuestra Señora de Las Caldas de Besaya, firmada por el arquitecto cántabro Lucas Gutiérrez de Vargas, junto al pleito que éste mantuvo con los dominicos en relación a su edificación. Ambos documentos aportan nuevos datos sobre la estrecha vinculación que guarda este edificio barroco con la arquitectura vallisoletana.A design of Nuestra Señora de Las Caldas de Besaya convent that was signed by the Cantabrian architect Lucas Gutiérrez de Vargas is kept at the Archives of the Real Chancillería of Valladolid, along with the litigation that the architect took against the Dominican Brothers in relation to its construction. Both documents provide new information on the close link between this Baroque building and religious architecture of Valladolid
Competitividad versus crecimiento en destinos turísticos. Un análisis mediante técnicas multivariantes
Baire category results for quasi–copulas
AbstractThe aim of this manuscript is to determine the relative size of several functions (copulas, quasi–
copulas) that are commonly used in stochastic modeling. It is shown that the class of all quasi–copulas that
are (locally) associated to a doubly stochastic signed measure is a set of first category in the class of all quasi–
copulas. Moreover, it is proved that copulas are nowhere dense in the class of quasi-copulas. The results are
obtained via a checkerboard approximation of quasi–copulas
Baire category results for stochastic orders
In the sense of Baire categories, we prove that the elements of a typical pair of univariate distribution functions (defined on a bounded subset of R) cannot be compared in the sense of the usual stochastic order, the increasing convex order and the mean residual lifetime order. A similar result is also proved in the class of copulas, i.e. multivariate distribution functions with standard uniform marginals, equipped with the orthant order
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