Parametric & nonparametric approaches to event studies: an application to a hotel’s market value

The main objective of this paper is twofold: on the one hand, to analyse the impact that the announcement of the opening of a new hotel has on the performance of its chain by carrying out an event study, and on the other hand, to compare the results of two different approaches to this method: a parametric specification based on the autoregressive conditional heteroskedasticity models to estimate the market model, and a nonparametric approach, which implies employing Theil’s nonparametric regression technique, which in turn, leads to the so-called complete nonparametric approach to event studies. The results that the empirical application arrives at are noteworthy as, on average, the reaction to such news releases is highly positive, both approaches reaching the same level of significance. However, a word of caution must be said when one is not only interested in detecting whether the market reacts, but also in obtaining an exhaustive calculation of the abnormal returns to further examine its determining factors.

Looking twice at the gender equity index for public health impact

Background: It has been shown that gender equity has a positive impact on the everyday activities of people (decision making, income allocation, application and observance of norms/rules) which affect their health. Gender equity is also a crucial determinant of health inequalities at national level; thus, monitoring is important for surveillance of women’s and men’s health as well as for future health policy initiatives. The Gender Equity Index (GEI) was designed to show inequity solely towards women. Given that the value under scrutiny is equity, in this paper a modified version of the GEI is proposed, the MGEI, which highlights the inequities affecting both sexes. Methods: Rather than calculating gender gaps by means of a quotient of proportions, gaps in the MGEI are expressed in absolute terms (differences in proportions). The Spearman’s rank coefficient, calculated from country rankings obtained according to both indexes, was used to evaluate the level of concordance between both classifications. To compare the degree of sensitivity and obtain the inequity by the two methods, the variation coefficient of the GEI and MGEI values was calculated. Results: Country rankings according to GEI and MGEI values showed a high correlation (rank coef. = 0.95). The MGEI presented greater dispersion (43.8%) than the GEI (19.27%). Inequity towards men was identified in the education gap (rank coef. = 0.36) when using the MGEI. According to this method, many countries shared the same absolute value for education but with opposite signs, for example Azerbaijan (−0.022) and Belgium (0.022), reflecting inequity towards women and men, respectively. This also occurred in the empowerment gap with the technical and professional job component (Brunei:-0.120 vs. Australia, Canada Iceland and the U.S.A.: 0.120). Conclusion: The MGEI identifies and highlights the different areas of inequities between gender groups. It thus overcomes the shortcomings of the GEI related to the aim for which this latter was created, namely measuring gender equity, and is therefore of great use to policy makers who wish to understand and monitor the results of specific equity policies and to determine the length of time for which these policies should be maintained in order to correct long-standing structural discrimination against women.

Oblique surface waves at an interface between a metal–dielectric superlattice and an isotropic dielectric

We investigate the existence and dispersion characteristics of surface waves that propagate at an interface between a metal–dielectric superlattice and an isotropic dielectric. Within the long-wavelength limit, when the effective-medium (EM) approximation is valid, the superlattice behaves like a uniaxial plasmonic crystal with the main optical axes perpendicular to the metal–dielectric interfaces. We demonstrate that if such a semi-infinite plasmonic crystal is cut normally to the layer interfaces and brought into contact with a semi-infinite dielectric, a new type of surface mode can appear. Such modes can propagate obliquely to the optical axes if favorable conditions regarding the thickness of the layers and the dielectric permittivities of the constituent materials are met. We show that losses within the metallic layers can be substantially reduced by making the layers sufficiently thin. At the same time, a dramatic enlargement of the range of angles for oblique propagation of the new surface modes is observed. This can lead, however, to field non-locality and consequently to failure of the EM approximation.

Mercury determination in urine samples by gold nanostructured screen-printed carbon electrodes after vortex-assisted ionic liquid dispersive liquid–liquid microextraction

A novel approach is presented to determine mercury in urine samples, employing vortex-assisted ionic liquid dispersive liquid–liquid microextraction and microvolume back-extraction to prepare samples, and screen-printed electrodes modified with gold nanoparticles for voltammetric analysis. Mercury was extracted directly from non-digested urine samples in a water-immiscible ionic liquid, being back-extracted into an acidic aqueous solution. Subsequently, it was determined using gold nanoparticle-modified screen-printed electrodes. Under optimized microextraction conditions, standard addition calibration was applied to urine samples containing 5, 10 and 15 μg L−1 of mercury. Standard addition calibration curves using standards between 0 and 20 μg L−1 gave a high level of linearity with correlation coefficients ranging from 0.990 to 0.999 (N = 5). The limit of detection was empirical and statistically evaluated, obtaining values that ranged from 0.5 to 1.5 μg L−1, and from 1.1 to 1.3 μg L−1, respectively, which are significantly lower than the threshold level established by the World Health Organization for normal mercury content in urine (i.e., 10–20 μg L−1). A certified reference material (REC-8848/Level II) was analyzed to assess method accuracy finding 87% and 3 μg L−1 as the recovery (trueness) and standard deviation values, respectively. Finally, the method was used to analyze spiked urine samples, obtaining good agreement between spiked and found concentrations (recovery ranged from 97 to 100%).

Diferencias en las atribuciones académicas en lengua en base al efecto positivo

La finalidad de esta investigación residió en conocer si los individuos pertenecientes a población infantil española con altas puntuaciones en Afecto Positivo (AP) poseían diferencias estadísticamente significativas con los individuos con bajas puntuaciones en AP en las seis dimensiones que componen las atribuciones académicas en el área de Lengua (Éxito: capacidad, esfuerzo y causas externas; Fracaso: capacidad, esfuerzo y causas externas). La muestra estaba compuesta por 862 estudiantes, entre 8 y 11 años. Se utilizó la subescala de lengua de la Sydney Attribution Scale (SAS) y la subescala de AP del Positive And Negative Affect Schedule for Children (PANAS-C) versión reducida. La prueba t de Student reflejó que los participantes con altos niveles de AP obtuvieron medias significativamente más altas en la atribución al éxito y al fracaso en Lengua a causas externas. Por otro lado, los sujetos con bajas puntuaciones en AP obtuvieron medias significativamente más altas en la atribución del fracaso en Lengua a la capacidad y al esfuerzo. Los resultados obtenidos complementan la literatura previa existente y dejan la posibilidad a seguir ampliando el campo del conocimiento del afecto y de las atribuciones académicas.

La evaluación de los aprendizajes en los sMOOC. Estudio de caso en el Proyecto Europeo ECO

El siguiente artículo hace una reflexión crítica sobre los MOOC, prestando especial atención al análisis de los nuevos sistemas de evaluación; en concreto, el método peer to peer, y cómo esto afecta al rol de docentes y estudiantes. El estudio se ha llevado a cabo tomando como referencia dos sMOOC liderados por el Proyecto Europeo ECO (Elearning, Communication and Open-data: Massive Mobile, Ubiquitous and Open Learning). Los resultados que se presentan han sido analizados desde una perspectiva cuantitativa, utilizando como muestra a los miembros de la comunidad de aprendizaje que han participado en ambos cursos. A través de la utilización de un cuestionario se ha podido conocer cómo han valorado su experiencia formativa y su grado de satisfacción. La mitad de los sujetos encuestados ha considerado adecuado y justo el nuevo sistema evaluativo, sin embargo existe otra mitad que lo considera injusto y que tiene lagunas. Se ha abordado la evaluación como una parte intrínseca del proceso educativo y por ello se ha enfatizado en aspectos como el empoderamiento del alumnado, la cultura de la participación y la interacción social, conceptos que nos acercan a nuevos modelos de aprendizaje que potencian el intelecto colectivo y dejan atrás sistemas transmisivos de conocimiento.