Search results for "multivariate"
showing 10 items of 1520 documents
Análisis de la realidad sociolingüística del valenciano
2011
Se analiza la situación actual del uso y la percepción social del valenciano entre los habitantes del País Valenciano a partir de los estudios realizados por el Centro de Investigaciones Sociológicas. Para ello, se presta especial atención a variables sociodemográficas a partir de análisis estadístico multivariante con distribuciones de frecuencias bivariadas, análisis de segmentación y regresión logística. El estudio concluye que se produce un estancamiento en el porcentaje de hablantes del valenciano y que las personas de izquierdas y con mayor nivel de estudios son quienes se postulan más a favor de la unidad del valenciano con el catalán. Palabras clave: sociolingüística; diglosia; esta…
A typology of theatre audiences based on the impact of various sources of influence and the use of information channels
2020
En: Doxa Comunicación: revista interdisciplinar de estudios de comunicación y ciencias sociales. e-ISSN 2386-3978 n. 30, 2020, pp 127-143. Este estudio presenta una tipología de espectadores teatrales que contempla la influencia de los medios de comunicación y otras instancias de prescripción en sus decisiones de asistencia al teatro, un aspecto no abordado por ninguna investigación previa. La investigación se basa en una encuesta a 210 asistentes a representaciones teatrales de tres salas de la ciudad de Valencia. La aplicación de diversas técnicas estadísticas multivariables ha permitido identificar una tipología de cuatro perfiles de consumidores escénicos: los informados-alternativos, l…
Multivariate geostatistics for assessing and predicting soil compaction
2005
The aim of this research is to investigate the potential of geostatistical techniques for understanding and evaluating the spatial variability of soil compaction, caused by the traffic of agricultural machines and/or the action of tillage implements. Soil cone penetrometer resistance was measured in a field of inland Sicily, along a transect of 3 m length, from the soil surface until 70 cm depth. The 3D mean maps showed a random variation on the surface and a high spatial correlation among penetrometer resistance data measured at different depths. The map corresponding to five tractor passes showed the largest extension of the areas characterised by the highest values of penetrometer resist…
Curative therapies are superior to standard of care (transarterial chemoembolization) for intermediate stage hepatocellular carcinoma.
2017
Background and aims the Barcelona Clinic Liver Cancer intermediate stage (BCLC-B) of hepatocellular carcinoma (HCC) includes extremely heterogeneous patients in terms of tumor burden and liver function. Transarterial-chemoembolization (TACE) is the first-line treatment for these patients although it may be risky/useless for someone, while others could undergo curative treatments. This study assesses the treatment type performed in a large cohort of BCLC-B patients and its outcome. Methods retrospective analysis of 485 consecutive BCLC-B patients from the ITA.LI.CA database diagnosed with naive HCC after 1999. Patients were stratified by treatment. Results 29 patients (6%) were lost to follo…
Near Infrared Spectroscopy Detection and Quantification of Herbal Medicines Adulterated with Sibutramine.
2015
There is an increasing demand for herbal medicines in weight loss treatment. Some synthetic chemicals, such as sibutramine (SB), have been detected as adulterants in herbal formulations. In this study, two strategies using near infrared (NIR) spectroscopy have been developed to evaluate potential adulteration of herbal medicines with SB: a qualitative screening approach and a quantitative methodology based on multivariate calibration. Samples were composed by products commercialized as herbal medicines, as well as by laboratory adulterated samples. Spectra were obtained in the range of 14,000-4000 per cm. Using PLS-DA, a correct classification of 100% was achieved for the external validatio…
Joint Graph Learning and Signal Recovery via Kalman Filter for Multivariate Auto-Regressive Processes
2018
In this paper, an adaptive Kalman filter algorithm is proposed for simultaneous graph topology learning and graph signal recovery from noisy time series. Each time series corresponds to one node of the graph and underlying graph edges express the causality among nodes. We assume that graph signals are generated via a multivariate auto-regressive processes (MAR), generated by an innovation noise and graph weight matrices. Then we relate the state transition matrix of Kalman filter to the graph weight matrices since both of them can play the role of signal propagation and transition. Our proposed Kalman filter for MAR processes, called KF-MAR, runs three main steps; prediction, update, and le…
The Multivariate Individual Selection of Diagnostic Tests and the Reserved Diagnostic Statement: An Optimum Combination of Two New Methods for the Co…
1984
A combination of two new methods for the diagnostic procedure in computer-aided differential diagnosis is presented. It is constructed on the basis of new results of our own in the field of mathematical decision theory and is demonstrated by the differential diagnosis of congenital heart diseases by means of ECG features.
Effects of morphometric descriptor changes on statistical classification and morphospaces
2004
Ten morphometric descriptors (five pairs of form and shape parameters) are used to describe the complex morphology of the first lower molar of two morphologically similar species, Microtus arvalis and M. agrestis. These descriptors are derived either from linear measurements or from outline analysis. The effects of these different descriptors on classical analysis as used in biology or palaeobiology are explored. First, the reliability of results in statistical classification is assessed. All of the descriptors discriminate well between the two species. The initial morphometric scheme (linear or outline) does not induce marked differences in statistical classification and the major discrepa…
The size of Simes’ global test for discrete test statistics
1999
Abstract To increase the power of the Bonferroni–Holm procedure several modified Bonferroni procedures have been proposed (for example, Hochberg, 1988. Biometrika 75, 800–802; Hommel, 1988. Biometrika 75, 383–386), which are based on Simes’ global test (Simes, 1986. Biometrika 73, 751–754). By several simulation studies which, in particular, considered multinormal test statistics, it has been suggested that the Simes test is a level α test. However, an exact proof exists for only few situations one of them assuming independence of test statistics. We studied the behaviour of Simes’ test for discrete test statistics. Due to discreteness one can expect more conservative decisions whereas depe…
On Independent Component Analysis with Stochastic Volatility Models
2017
Consider a multivariate time series where each component series is assumed to be a linear mixture of latent mutually independent stationary time series. Classical independent component analysis (ICA) tools, such as fastICA, are often used to extract latent series, but they don't utilize any information on temporal dependence. Also financial time series often have periods of low and high volatility. In such settings second order source separation methods, such as SOBI, fail. We review here some classical methods used for time series with stochastic volatility, and suggest modifications of them by proposing a family of vSOBI estimators. These estimators use different nonlinearity functions to…