940 resultados para Factor Analysis, Statistical


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In this work, we propose the Seasonal Dynamic Factor Analysis (SeaDFA), an extension of Nonstationary Dynamic Factor Analysis, through which one can deal with dimensionality reduction in vectors of time series in such a way that both common and specific components are extracted. Furthermore, common factors are able to capture not only regular dynamics (stationary or not) but also seasonal ones, by means of the common factors following a multiplicative seasonal VARIMA(p, d, q) × (P, D, Q)s model. Additionally, a bootstrap procedure that does not need a backward representation of the model is proposed to be able to make inference for all the parameters in the model. A bootstrap scheme developed for forecasting includes uncertainty due to parameter estimation, allowing enhanced coverage of forecasting intervals. A challenging application is provided. The new proposed model and a bootstrap scheme are applied to an innovative subject in electricity markets: the computation of long-term point forecasts and prediction intervals of electricity prices. Several appendices with technical details, an illustrative example, and an additional table are available online as Supplementary Materials.

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Se investiga la distribución espacial de contenidos metálicos analizados sobre testigos de sondeos obtenidos en las campañas de exploración de la Veta Pallancata. Se aplica el análisis factorial a dicha distribución y a los cocientes de los valores metálicos, discriminando los que están correlacionados con la mineralización argentífera y que sirven como guías de exploración para hallar zonas de potenciales reservas por sus gradientes de variación.Abstract:The metal distribution in a vein may show the paths of hydrothermal fluid flow at the time of mineralization. Such information may assist for in-fill drilling. The Pallancata Vein has been intersected by 52 drill holes, whose cores were sampled and analysed, and the results plotted to examine the mineralisation trends. The spatial distribution of the ore is observed from the logAg/logPb ratio distribution. Au is in this case closely related to Ag (electrum and uytenbogaardtite, Ag3AuS2 ). The Au grade shows the same spatial distribution as the Ag grade. The logAg/logPb ratio distribution also suggests possible ore to be expected at deeper locations. Shallow supergene Ag enrichment was also observed.

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Includes bibliographies (p. 31).

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Cover title.

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Previous research shows that correlations tend to increase in magnitude when individuals are aggregated across groups. This suggests that uncorrelated constellations of personality variables (such as the primary scales of Extraversion and Neuroticism) may display much higher correlations in aggregate factor analysis. We hypothesize and report that individual level factor analysis can be explained in terms of Giant Three (or Big Five) descriptions of personality, whereas aggregate level factor analysis can be explained in terms of Gray's physiological based model. Although alternative interpretations exist, aggregate level factor analysis may correctly identify the basis of an individual's personality as a result of better reliability of measures due to aggregation. We discuss the implications of this form of analysis in terms of construct validity, personality theory, and its applicability in general. Copyright (C) 2003 John Wiley Sons, Ltd.