Observational data analysis using generalizability theory and general and mixed linear models: An empirical study of infant learning and development

Accurate evaluation of early childhood competencies is essential for favoring optimal development, as the first years of life form the foundations for later learning and development. Nonetheless, there are still certain limitations and deficiencies related to how infant learning and development are measured. With the aim of helping to overcome some of the difficulties, in this article we describe the potential and advantages of new data analysis techniques for checking the quality of data collected by the systematic observation of infants and assessing variability. Logical and executive activity of 48 children was observed in three ages (18, 21 and 24 months) using a nomothetic, follow-up and multidimensional observational design. Given the nature of the data analyzed, we provide a detailed methodological and analytical overview of generalizability theory from three perspectives linked to observational methodology: intra- and inter-observer reliability, instrument validity, and sample size estimation, with a particular focus on the participant facet. The aim was to identify the optimal number of facets and levels needed to perform a systematic observational study of very young children. We also discuss the use of other techniques such as general and mixed linear models to analyze variability of learning and development. Results show how the use of Generalizability Theory allows controlling the quality of observational data in a global structure integrating reliability, validity and generalizability. Una adecuada evaluación de las competencias infantiles tem-pranas es esencial para potenciar un desarrollo óptimo, pues los primeros años de vida son la base de todo el desarrollo y aprendizaje posterior. Sin embargo, todavía existen ciertas limitaciones y deficiencias en el ámbito de la medición del desarrollo y aprendizaje infantil. Con el objetivo último de contribuir a la mejora de esta situación, este trabajo presenta las posibilida-des y ventajas que ofrecen nuevas técnicas de análisis de datos, tanto para controlar la calidad de los datos infantiles registrados a través de observa-ción sistemática como para analizar su variabilidad. Se ha observado en tres edades diferentes (18, 21 y 24 meses) la actividad lógica y ejecutiva de 48 niños usando un diseño observacional nomotético, de seguimiento y mul-tidimensional. Dadas las particularidades de los datos del estudio que presentamos, desde el punto de vista metodológico y su análisis, realizamos análisis pormenori-zados a través de la Teoría de la Generalizabilidad en tres vertientes posi-bles en un estudio observacional: Análisis de la fiabilidad intra e inter-observadores, Análisis de la validez del instrumento de observación y Es-timación muestral de las facetas estudiadas (en concreto, la de participan-tes). De esta forma, se pretende optimizar el número de facetas y niveles necesarios para llevar a cabo un estudio de tales características. Además, se utilizan otras técnicas analíticas para conocer la variabilidad del desarrollo y aprendizaje infantil, como son el Modelo Lineal General y el Modelo MIXED. Los resultados indican cómo el uso de la Teoría de la Generalizabilidad permite controlar la calidad de los datos observacionales en una estructura única que integra la fiabilidad, validad y generalizabilidad

Observational effects of magnetism in O stars: surface nitrogen abundances

We investigate the surface nitrogen content of the six magnetic O stars known to date as well as of the early B-type star tau Sco. We compare these abundances to predictions of evolutionary models to isolate the effects of magnetic field on the transport of elements in stellar interiors. We conduct a quantitative spectroscopic analysis of the sample stars with state-of-the-art atmosphere models. We rely on high signal-to-noise ratio, high resolution optical spectra obtained with ESPADONS at CFHT and NARVAL at TBL. Atmosphere models and synthetic spectra are computed with the code CMFGEN. Values of N/H together with their uncertainties are determined and compared to predictions of evolutionary models. We find that the magnetic stars can be divided into two groups: one with stars displaying no N enrichment (one object); and one with stars most likely showing extra N enrichment (5 objects). For one star (Theta1 Ori C) no robust conclusion can be drawn due to its young age. The star with no N enrichment is the one with the weakest magnetic field, possibly of dynamo origin. It might be a star having experienced strong magnetic braking under the condition of solid body rotation, but its rotational velocity is still relatively large. The five stars with high N content were probably slow rotators on the zero age main sequence, but they have surface N/H typical of normal O stars, indicating that the presence of a (probably fossil) magnetic field leads to extra enrichment. These stars may have a strong differential rotation inducing shear mixing. Our results should be viewed as a basis on which new theoretical simulations can rely to better understand the effect of magnetism on the evolution of massive stars.Comment: 14 pages, 6 figures. Accepted by A&

Open data on Covid-19 in the Spanish autonomous communities: reutilization in spatial epidemiology studies

The Covid-19 pandemic has highlighted the need for governments and health administrations at all levels to have an open data registry that facilitates decision-making in the planning and management of health resources and provides information to citizens on the evolution of the epidemic. The concept of “open data” includes the possibility of reutilization by third parties. Space and time are basic dimensions used to structure and interpret the data of the variables that refer to the health status of the people themselves. Hence, the main objective of this study is to evaluate whether the autonomous communities’ data files regarding Covid-19 are reusable to analyze the evolution of the disease in basic spatial and temporal analysis units at the regional and national levels. To this end, open data files containing the number of diagnosed cases of Covid-19 distributed in basic health or administrative spatial units and temporal units were selected from the portals of the Spanish autonomous communities. The presence of infection-related, demographic, and temporal variables, as well as the download format and metadata, were mainly evaluated. Whether the structure of the files was homogeneous and adequate for the application of spatial analysis techniques was also analyzed. The results reveal a lack of standardization in the collection of data in both spatial and temporal units and an absence of, or ambiguity in, the meaning of the variables owing to a lack of metadata. An inadequate structure was also found in the files of seven autonomous communities, which would require subsequent processing of the data to enable their reuse and the application of analysis and spatial modeling techniques, both when carrying out global analyses and when comparing patterns of evolution between different regions

Estrategias utilizadas por estudiantes de distintos niveles educativos ante problemas de proporcionalidad compuesta

En este trabajo se analizan las actuaciones de alumnos desde 6.º de Educación Primaria hasta 2.º de Educación Secundaria Obligatoria (11-14 años) con distintos grados de instrucción en proporcionalidad al resolver ciertos problemas de proporcionalidad compuesta. En particular, observamos la tasa de éxito y las distintas estrategias empleadas, tanto correctas como incorrectas. Los resultados muestran un aumento progresivo de la tasa de éxito y una evolución en las estrategias utilizadas desde aquellas que hacen referencia a aspectos de razonamiento proporcional, hacia aquellas en las que prima el componente algorítmico

Analyzing and Decoding Natural Reach-and-Grasp Actions Using Gel, Water and Dry EEG Systems

Reaching and grasping is an essential part of everybody’s life, it allows meaningful interaction with the environment and is key to independent lifestyle. Recent electroencephalogram (EEG)-based studies have already shown that neural correlates of natural reach-and-grasp actions can be identified in the EEG. However, it is still in question whether these results obtained in a laboratory environment can make the transition to mobile applicable EEG systems for home use. In the current study, we investigated whether EEG-based correlates of natural reach-and-grasp actions can be successfully identified and decoded using mobile EEG systems, namely the water-based EEG-VersatileTM system and the dry-electrodes EEG-HeroTM headset. In addition, we also analyzed gel-based recordings obtained in a laboratory environment (g.USBamp/g.Ladybird, gold standard), which followed the same experimental parameters. For each recording system, 15 study participants performed 80 self-initiated reach-and-grasp actions toward a glass (palmar grasp) and a spoon (lateral grasp). Our results confirmed that EEG-based correlates of reach-and-grasp actions can be successfully identified using these mobile systems. In a single-trial multiclass-based decoding approach, which incorporated both movement conditions and rest, we could show that the low frequency time domain (LFTD) correlates were also decodable. Grand average peak accuracy calculated on unseen test data yielded for the water-based electrode system 62.3% (9.2% STD), whereas for the dry-electrodes headset reached 56.4% (8% STD). For the gel-based electrode system 61.3% (8.6% STD) could be achieved. To foster and promote further investigations in the field of EEG-based movement decoding, as well as to allow the interested community to make their own conclusions, we provide all datasets publicly available in the BNCI Horizon 2020 database (http://bnci-horizon-2020.eu/database/data-sets)

Locally nilpotent linear groups with the weak chain conditions on subgroups of infinite central dimension

Let V be a vector space over a field F. If G≤GL(V, F), the central dimension of G is the F-dimension of the vector space V/CV (G). In [DEK] and [KS], soluble linear groups in which the set Licd(G) of all proper infinite central dimensional subgroups of G satisfies the minimal condition and the maximal condition, respectively, have been described. On the other hand, in [MOS], periodic locally radical linear groups in which Licd(G) satisfies one of the weak chain conditions (the weak minimal condition or the weak maximal condition) have been characterized. In this paper, we begin the study of the non-periodic case by describing locally nilpotent linear groups in which Licd(G) satisfies one of the two weak chain conditions

Characterization of behavior of correctors when grading mathematics tests

In this work, we present some results obtained from the analysis of the behavior of 91 mathematics teachers (prospective, secondary education and university) when they grade three different types of correct answers to a classical high school problem through a questionnaire. In addition to a descriptive analysis that studies the variability and the interrater reliability, we analyze the role of experience and training as well as the influence of the different solving methods. Furthermore, we try to identify profiles of correctors among secondary education teachers using both quantitative (cluster analysis) and qualitative (content analysis) methods. In particular, we observe a great variability on the assigned grades as well as a low interrater reliability. The belonging to a particular group has impact over the assigned rates while experience has no significant influence. The grades are higher when methods closer to the corrector are used. Finally, we have been able to identify three different clusters, which are determined by the comments and actions regarding three aspects of the students’ answers: argumentation, correctness and method

Esquemas de prueba en torno al concepto de proporcionalidad en los libros de texto

Además de su valor matemático, la importancia de la demostración desde el punto de vista de la Educación Matemática está ampliamente aceptada. La actividad demostrativa suele reservarse para los cursos superiores (Bachillerato o Universidad) por ser un proceso complejo. Sin embargo, existen numerosos autores que abogan por la introducción de este proceso en etapas previas. Así, Vallejo y Ordóñez (2015) realizan una experiencia con alumnos de 7-8 años que argumentan para justificar una afirmación relacionada con la división de números naturales. Stylianides y Stylianides (2009) consideran, en base a criterios educativos y psicológicos, que es apropiado y razonable introducir la demostración y el razonamiento deductivo en niveles inferiores al instituto