Search results for "regression"
showing 10 items of 2619 documents
Agreement among 3 optical imaging methods for the assessment of optic disc topography.
2005
Purpose To assess the agreement of disc topography measurements between the Heidelberg Retina Tomograph (HRT II), Retinal Thickness Analyzer (RTA), and Optical Coherence Tomograph (StratusOCT). Design Observational cross-sectional study. Participants Forty-two randomly chosen eyes of 42 subjects. Methods Each subject underwent HRT II, RTA, and StratusOCT examination. Two experienced examiners drew the contour lines for the HRT II and RTA. Bland and Altman plots were used to evaluate agreement for each topographic parameter among the instruments. The Spearman coefficient of rank correlation was evaluated for each topographic parameter. Main Outcome Measures Agreement in the measurement of op…
Factors associated with early recurrence at the first evaluation of patients with transient ischemic attack.
2014
Abstract We aimed to identify factors easily collected at admission in patients with transient ischemic attack (TIA) that were associated with early recurrence, so as to guide clinicians’ decision-making about hospitalization in routine practice. From September 2011 to January 2013, all TIA patients who were referred to the University Hospital of Dijon, France, were identified. Vascular risk factors and clinical information were collected. The etiology of the TIA was defined according to the results of complementary examinations performed at admission as follows: large artery atherosclerosis (LAA-TIA) TIA, TIA due to atrial fibrillation (AF-TIA), other causes, and undetermined TIA. Logistic…
Funcionamiento diferencial del ítem de la evaluación internacional PISA. Detección y comprensión
2014
Este trabajo analiza el funcionamiento diferencial del ítem (FDI) de la prueba de comprensión lectora de la evaluación PISA2000 entre la muestras del Reino Unido y España. Se estudian los ítems liberados con el fin de aunar las fases de detección del FDI con la comprensión de sus causas. En la fase de detección se comparan los resultados de los procedimientos Mantel-Haenszel, Regresión Logística y Medias Estandarizadas en sus versiones para ítems dicotómicos y politómicos. Los resultados muestran que dos ítems presentan funcionamiento diferencial aunque el estudio post-hoc llevado a cabo sobre su contenido no ha podido precisar sus causas.
THE RELATIONSHIP BETWEEN DIFFUSE AND TOTAL SOLAR RADIATION IN COMPUTER SIMULATION OF SOLAR ENERGY SYSTEMS
1978
ABSTRACT The diffuse to total radiation correlation developed by Liu and Jordan [1] was tested for three Italian locations. An acceptable agreement was found between the regression lines in [1] and the ones found for two of the three locations. Using measured hourly values of total solar radiation on a horizontal surface, the corresponding hourly values of total solar radiation on an inclined surface at 45° facing south were computed with both the Liu and Jordan and the Loudon [6] method for estimating the diffuse radiation. Results show that approximately the same degree of accuracy in the prediction is achievable with both methods and that the difference between the measured total monthly…
Characterization of estuarine sediments by near infrared diffuse reflectance spectroscopy
2008
It has been developed a partial least squares near infrared (PLS-NIR) method for the determination of estuarine sediment physicochemical parameters. The method was based on the chemometric treatment of first order derivative reflectance spectra obtained from samples previously lyophilized and sieved through a lower than 63 μm grid. Spectra were scanned from 833 to 2976 nm, averaging 36 scans per spectrum at a resolution of 8 cm-1, using chromatographic glass vials of 9.5 mm internal diameter as measurement cells. Models were built using reference data of 31 samples selected through the use of a hierarchical cluster analysis of NIR spectra of sediments obtained from the Ria de Arousa estuary…
Regression Wavelet Analysis for Lossless Coding of Remote-Sensing Data
2016
A novel wavelet-based scheme to increase coefficient independence in hyperspectral images is introduced for lossless coding. The proposed regression wavelet analysis (RWA) uses multivariate regression to exploit the relationships among wavelet-transformed components. It builds on our previous nonlinear schemes that estimate each coefficient from neighbor coefficients. Specifically, RWA performs a pyramidal estimation in the wavelet domain, thus reducing the statistical relations in the residuals and the energy of the representation compared to existing wavelet-based schemes. We propose three regression models to address the issues concerning estimation accuracy, component scalability, and c…
Air conditioning and heat-related mortality: a multi-country longitudinal study
2020
Background: Air conditioning has been proposed as one of the key factors explaining reductions of heat-related mortality risks observed in the last decades. However, direct evidence is still limited. Methods: We used a multi-country, multi-city, longitudinal design to quantify the independent role of air conditioning in reported attenuation in risk. We collected daily time series of mortality, mean temperature, and yearly air conditioning prevalence for 311 locations in Canada, Japan, Spain, and the USA between 1972 and 2009. For each city and sub-period, we fitted a quasi-Poisson regression combined with distributed lag non-linear models to estimate summer-only temperature–mortality associ…
U.S. stock prices and macroeconomic fundamentals: Fresh evidence using the quantile ARDL approach
2020
This paper explores the long‐run relationship and the associated short‐run dynamics between the U.S. stock market and three major macroeconomic fundamentals, namely the U.S. industrial production index, the U.S. 10‐year Treasury bond yield and the West Texas Intermediate oil price, for the time period covering 1985–2015. The quantile autoregressive distributed lag (QARDL) model presented by Cho et al. (2015) Journal of Econometrics, 188, 281–300, which combines the autoregressive distributed lag model of Pesaran and Shin (1998), Cambridge University Press, and Pesaran et al. (2001) Journal of Applied Econometrics, 16, 289–326, and the quantile regression methodology of Koenker and Bassett (…
Comparison of temperature–mortality associations using observed weather station and reanalysis data in 52 Spanish cities
2020
Abstract Background Most studies use temperature observation data from weather stations near the analyzed region or city as the reference point for the exposure-response association. Climatic reanalysis data sets have already been used for climate studies, but are not yet used routinely in environmental epidemiology. Methods We compared the mortality-temperature association using weather station temperature and ERA-5 reanalysis data for the 52 provincial capital cities in Spain, using time-series regression with distributed lag non-linear models. Results The shape of temperature distribution is very close between the weather station and ERA-5 reanalysis data (correlation from 0.90 to 0.99).…
Impact of wage penalty on mobility return of French PhDs
2015
International audience; Expatriation of higher-education graduates raises much concern in many countries often in conjunction with talk about the brain drain. It supposedly entails a risk of losing the skills required for a competitive economy. The issue is all the more acute for PhD graduates, who are expected to play a major part in the knowledge economy. However, questions arise as to the causes of such mobility and its consequences for young graduates' individual career paths.