Search results for "multivariate"
showing 10 items of 1520 documents
A new species of Armeria (Plumbaginaceae) from southern Spain with molecular and morphometric evidence on its origin
2001
The definitive version is available at http://onlinelibrary.wiley.com/
Assessing Complexity in Physiological Systems through Biomedical Signals Analysis
2020
The idea that most physiological systems are complex has become increasingly popular in recent decades [...]
Social capital and political participation
2010
This paper analyzes the determinants of social capital, as generalized trust, from a microeconomic perspective. We review previous results at the aggregate level and test their significance in our setup. Specifically we aim at testing the role of political participation and the quality of institutions. The empirical work relies on microeconomic data from the 2008 wave of the European Social Survey, including 21 European countries and roughly 41,000 observations on a wide set of socio-economic and political variables. Preliminary results underline the role of political participation in the accumulation of generalized trust, while data are consistent with institutional quality being a consequ…
CLUSTERING INCOMPLETE SPECTRAL DATA WITH ROBUST METHODS
2018
Abstract. Missing value imputation is a common approach for preprocessing incomplete data sets. In case of data clustering, imputation methods may cause unexpected bias because they may change the underlying structure of the data. In order to avoid prior imputation of missing values the computational operations must be projected on the available data values. In this paper, we apply a robust nan-K-spatmed algorithm to the clustering problem on hyperspectral image data. Robust statistics, such as multivariate medians, are more insensitive to outliers than classical statistics relying on the Gaussian assumptions. They are, however, computationally more intractable due to the lack of closed-for…
The Influence of an Enriched Sport Program on Children’s Sport Motivation in the School Context: The ESA PROGRAM
2020
Purpose: Besides the evident positive effect on body development, physical activity has proven to boost executive functions, especially if the exercises are enriched with cognitive stimuli. Previous studies have shown that introducing challenging exercises in the physical activity routine can also enhance motivation. Therefore, enriching a physical education program with cognitively challenging exercises may also foster children’s motivation during physical education classes, where the motivation is high at the beginning of the school year and low at the end of it. Therefore, the purpose of this paper is to test if a sport program enriched by cognitive stimuli may improve kids’ motivation o…
Multi-elemental EDXRF mapping of polluted soil from former horticultural land.
2004
The distribution of major and trace elements was systematically investigated by use of energy dispersive X-ray fluorescence spectrometry (EDXRF) on a former horticultural soil. The purpose of the study was to combine mapping of soil element concentration levels with multivariate statistics for characterisation of soil metal pollution in relation to previous and present land use. A 1-ha study site was chosen from a former horticulture where a previous preliminary survey indicated increased concentration levels of toxic elements. The soil was sampled from the top 20 cm of the soil surface in a 10×10-m grid-like pattern covering the 1-ha study area. In addition, three soil profiles were studie…
Comparative Analysis of Spatial Interpolation Methods in the Mediterranean Area: Application to Temperature in Sicily
2015
An exhaustive comparison among different spatial interpolation algorithms was carried out in order to derive annual and monthly air temperature maps for Sicily (Italy). Deterministic, data-driven and geostatistics algorithms were used, in some cases adding the elevation information and other physiographic variables to improve the performance of interpolation techniques and the reconstruction of the air temperature field. The dataset is given by air temperature data coming from 84 stations spread around the island of Sicily. The interpolation algorithms were optimized by using a subset of the available dataset, while the remaining subset was used to validate the results in terms of the accur…
Students’ physical activity intensity and sedentary behaviour by physical self-concept profiles: A latent profile analysis. [Intensidad de la activid…
2020
Abstract Aims of this study were to identify student clusters in physical appearance, sport competence, global physical self-concept and self-esteem, and to examine whether different physical self-concept groups differ in their moderate-to-vigorous physical activity (MVPA) and sedentary behaviour. Participants of the study were 211 boys and 183 girls aged 13-16 years. MVPA and sedentary behaviour were monitored by GT3X accelerometers during seven days. Participants’ physical self-concept was measured by the short Physical Self-Description Questionnaire. Latent profile analyses revealed a four-cluster solution: 1) “low sport competence, moderate global physical self-concept and self-esteem, …
Within-student variability in learning experiences, and teachers’ perceptions of students’ task-focus
2016
In order to advance models of educational processes (intraindividual, intensive longitudinal), we propose a model in which we specify state and trait constructs, and an intraindividual variability construct. In our ecological momentary assessment study, we investigated how trait-level and intraindividual variability of students’ learning experiences (intrinsic and extrinsic motivation, task difficulty, effort exertion, help-seeking and competence evaluations) converged with teacher-reported student task-focus. 285 primary school students’ (Years 5 and 6) completed the Learning Experience Questionnaire using handheld computers, on average 13.6 learning episodes during one week (SD = 4.6; Ran…
gllvm : Fast analysis of multivariate abundance data with generalized linear latent variable models in R
2019
1.There has been rapid development in tools for multivariate analysis based on fully specified statistical models or “joint models”. One approach attracting a lot of attention is generalized linear latent variable models (GLLVMs). However, software for fitting these models is typically slow and not practical for large datsets. 2.The R package gllvm offers relatively fast methods to fit GLLVMs via maximum likelihood, along with tools for model checking, visualization and inference. 3.The main advantage of the package over other implementations is speed e.g. being two orders of magnitude faster, and capable of handling thousands of response variables. These advances come from using variationa…