Search results for "Corrélation"
showing 10 items of 20 documents
Les Gregoryceras (Ammonitina) de l'Oxfordien moyen terminal et supérieur téthysien : révision systématique, biostratigraphie et évolution.
2009
43 pages; Les Gregoryceras Spath, 1924 (Ammonitina, Peltoceratina) de la fin de l'Oxfordien moyen (sous-zone à Rotoides) et de la base de l'Oxfordien supérieur (zone à Bifurcatus) sont révisés. Les coupes ayant fourni la plupart des spécimens de ce travail (Espagne et Maghreb) sont décrites et datées sur la base de comparaisons fauniques entre les domaines téthysien et subtéthysien. Le meilleur outil pour ces corrélations est la présence du genre Gregoryceras. La succession des espèces de Gregoryceras est identique pour les deux domaines suscités, ce qui permet de compléter l'échelle biostratigraphique proposée antérieurement et parallèle à la zonation standard. Les espèces reconnues et red…
Interannual memory effects for spring NDVI in semi-arid South Africa
2008
[1] Almost 20 years of Normalized Difference Vegetative Index (NDVI) and precipitation (PPT) data are analysed to better understand the interannual memory effects on vegetation dynamics observed at regional scales in Southern Africa (SA). The study focuses on a semi-arid region (25°S–31°S; 21°E–26°E) during the austral early summer (September–December). The memory effects are examined using simple statistical approaches (linear correlations and regressions) which require the definition of an early summer vegetation predictand (December NDVI minus September NDVI) and a consistent set of potential predictors (rainfall amount, number of rainy days, rainfall intensity, NDVI and Rain-Use-Efficie…
Perdió el libro que se compró / había comprado pocos días antes: Reflexiones iniciales en torno al saber gramatical sobre los tiempos verbales del pa…
2007
Carmen.Rdez-Gonzalo@uv.es La alternancia entre los tiempos verbales del pasado en textos escritos exige tener en cuenta diferencias aspectuales poco presentes en el español hablado. Según López García (2005: 162), el sistema de cinco tiempos simples (vengo, venía, vine, vendría, vendré) cubre las necesidades expresivas de los hispanohablantes, aunque los niños emplean menos y muchos hablantes adultos raramente usan otras formas. Los problemas se plantean cuando en lugar de hablar español necesitamos escribirlo y leerlo. Esta necesidad cambia por completo el inventario de tiempos ya que, para articular un texto es preciso dejar muy claro que unos acontecimientos ocurren antes o después de ot…
Estimation des modèles dynamiques à erreurs composées avec autocorrélation par la méthode des variables instrumentales
1996
In this paper, we consider a dynamic error-components models with autocorrelated disturbances. We analyse the efficient estimation procedure of autocorrelation parameter and we try to find out whether moment conditions of a dynamic model without autocorrelation are valid when the model includes autocorrelation. We propose two efficient estimation methods of autocorrelation parameter in addition to Baltagi and Li (1994) estimator. We show that all moment conditions of a dynamic model without autocorrelation are not valid in dynamics errors-components models with autocorrelated disturbances.
Behaviour of common estimators in dynamic error-components models with autocorrelated disturbances
1997
The purpose of this paper is to make a presentation of the properties of a set of estimators comprising the within, between, OLS and GLS estimators in the study of dynamic error - components models with autocorrelated disturbances. We underline in this study the importance of the statistical distribution governing the initial values for the process and the structure of xit variable for the limiting values of the estimators when the temporal dimension is fixed but the individual dimension N grows indefinitly.
Apprend-on mieux en école rurale ?
2007
07121
Sa méthode et la nôtre... Texte en réponse à l'étude de Thomas Piketty sur la taille des classes
2004
National audience
Résolution spatiale des MNT et qualité de l'estimation des températures et des précipitations en France
2015
DTM spatial resolution and temperature and amount of rainfall estimation in France. The spatial variationanalysis of normal temperature and amount of rainfall in France is performed by simple linear correlations where elevationis the explanatory variable. The latter is provided in seven resolutions: 250,500 m, 1, 2, 4, 8 and 16 km. The correlationcoefficient is used to assess what is the resolution that works best. Temperatures are optimally explained by the 250 mresolution, the coarser resolutions producing lower quality results. The 2km resolution best explains the spatial variation ofrainfall.
Online Detection and Removal of Eye Blink Artifacts from Electroencephalogram
2020
The most prominent type of artifact contaminating electroencephalogram (EEG)signals are the eyeblink (EB) artifacts, which could potentially lead tomisinterpretation of the EEG signal. Online detection and removal of eyeblink artifacts from EEG signals are essential in applications such a Brain-Computer Interfaces (BCI), neurofeedback and epilepsy diagnosis. In this thesis, algorithms that combine unsupervised eyeblink artifact detection (eADA) with enhanced Empirical Mode Decomposition (FastEMD) and Canonical Correlation Analysis (CCA) are proposed,i.e. FastEMD-CCA2 and FastCCA, to automatically identify eyeblink artifacts andremove them in an online setting. FastEMD-CCA2 and FastCCA have …
Économétrie spatiale : l'autocorrélation spatiale dans les modèles de régression linéaire
2002
Spatial Econometrics : Automatic Spatial Correlation in Linear Regression Models. The aim of this article is to describe the tools necessary to factor in automatic spatial correlation determined by the absence of independence between geographical observations, within the framework of linear regression models. While it is often accepted that spatial data in cross-sections are independent, this assumption is rarely justified. On the contrary, it needs to be tested systematically. After explaining the ways in which to model automatic spatial correlation, we therefore describe estimation and inference procedures geared to econometric models that factor in this effect explicitly. Lastly, we prop…