Search results for " Regression"
showing 10 items of 1835 documents
Antibiotic use and associated factors in a large sample of hospitalised older people
2019
Objectives: The aims of this study were to assess (i) the prevalence of antibiotic use, (ii) factors associated with their use and (iii) the association with in-hospital mortality in a large sample of hospitalised older people in Italy.Methods: Data were obtained from the 2010-2017 REPOSI register held in more than 100 internal medicine and geriatric wards in Italy. Patients aged >= 65 years with at least one antibiotic prescription during their hospitalisation were selected. Multivariable logistic regression models were used to determine factors associated with antibiotic use.Results: A total of 5442 older patients were included in the analysis, of whom 2786 (51.2%) were prescribed anti…
Fitting linear models and generalized linear models with large data sets in R
2009
We present an estimating algorithm to fit linear and generalized linear models not involving the QR decomposition. Some new R functions are presented and discussed. For large data sets, comparisons with respect to the well-known lm() and glm(), as well as to biglm() and bigglm() from the package biglm, show that the proposed functions speed up computation while preserving numerical stability and accuracy
A kernel regression approach to cloud and shadow detection in multitemporal images
2013
Earth observation satellites will provide in the next years time series with enough revisit time allowing a better surface monitoring. In this work, we propose a cloud screening and a cloud shadow detection method based on detecting abrupt changes in the temporal domain. It is considered that the time series follows smooth variations and abrupt changes in certain spectral features will be mainly due to the presence of clouds or cloud shadows. The method is based on linear and nonlinear regression analysis; in particular we focus on the regularized least squares and kernel regression methods. Experiments are carried out using Landsat 5 TM time series acquired over Albacete (Spain), and compa…
Discrete Time Signal Processing Framework with Support Vector Machines
2007
Digital signal processing (DSP) of time series using SVM has been addressed in the literature with a straightforward application of the SVM kernel regression, but the assumption of independently distributed samples in regression models is not fulfilled by a time-series problem. Therefore, a new branch of SVM algorithms has to be developed for the advantageous application of SVM concepts when we process data with underlying time-series structure. In this chapter, we summarize our past, present, and future proposal for the SVM-DSP frame-work, which consists of several principles for creating linear and nonlinear SVM algorithms devoted to DSP problems. First, the statement of linear signal mod…
Determination of the energetic value of fruit and milk-based beverages through partial-least-squares attenuated total reflectance-Fourier transform i…
2005
Abstract The estimation of important nutritional parameters, such as carbohydrates content and energetic value (calories) in commercially available fruit juice and flavour milk shakes has been made by attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) using a partial-least-square (PLS) calibration approach. A highly heterogeneous population of 65 samples obtained from the Spanish market, covering fruit juices, flavour milk shakes and milk-added fruit juices was used. The spectral range and the size of the calibration set for building the PLS model have been evaluated. Considering a calibration set comprised of 27 samples, selected via hierarchical cluster analys…
Associations between recently diagnosed conditions and hospitalization due to COVID-19 in patients aged 50 years and older– A SHARE-based analysis
2021
Abstract Background Only a few studies have been carried out with a large sample size on the relationship between chronic conditions and hospitalization for coronavirus disease 2019 (COVID-19), and there is no research examining recently diagnosed conditions. Our purpose was to evaluate this association in a large sample including the older population from Europe and Israel. Method Data from the Survey of Health, Ageing and Retirement in Europe COVID-19 Survey, a representative survey of individuals aged 50 or older residing in 27 European countries and Israel, were retrieved. Associations between recently diagnosed chronic conditions (ie, conditions detected over the last 3 years) (exposur…
Residential location and youth unemployment: The economic geography of school-to-work transitions
2003
In response to increased international policy attention to youth unemployment this study investigates post-secondary school transitions of school leavers. Multinomial logit models are estimated for male and female German youth. The models control for individual, parent, and household characteristics, for those of the youth’s region of residence and local labor markets. The findings suggest that immigrant youth has particularly low participation rates in continued education, and that youth unemployment is centered in high unemployment states and metropolitan areas. More generous academic benefit policies seem to be correlated with increased academic enrollment, and men’s transitions to the m…
Estuarine sediment quality assessment by Fourier-transform infrared spectroscopy
2010
Partial least squares Fourier-transform infrared (PLS-FTIR) models were developed for the quality assessment of estuarine sediments through the evaluation of several physico-chemical parameters. Models were based on the chemometric treatment of attenuated total reflection (ATR) spectra directly obtained from samples previously lyophilized and sieved through a lower than 63 μm grid. Spectra were scanned from 3997 to 523 cm-1, averaging 36 scans per spectrum with a nominal resolution of 8 cm-1. Models were built using reference data obtained for sediment samples collected from Ria de Arousa estuary. Hierarchical cluster classification of sediment ATR spectra was employed for the establishment…
Dental expenditure and catastrophic dental expenditure in Eastern Saudi Arabia: Pattern and associated factors
2019
Background Dental services have one of the highest expenses among health services. The aims of the study were to assess (1) dental expenditure (DE), (2) catastrophic dental expenditure (CDE), (3) dental services payment and (4) factors associated with DE and CDE. Material and methods A cross sectional study was conducted in 2018 in Saudi Arabia. Using convenience sample, participants were recruited from governmental and private dental clinics/hospitals. A questionnaire assessed (a) personal information, (b) dental background: payment methods, type of clinics visited, perceived oral health status, frequency of pain and (c) payment for dental services received. The number of remaining teeth w…
Quantitative ECG analysis for individual risk assessment of future myocardial infarct-results from the MARISK study
2002
From 1980 to 1990 the authors performed an epidemiological cohort study in order to explore the predictive power of computer electrocardiogram (ECG) measurements for individual risk assessment of future myocardial infarct in combination with commonly known risk factors. Out of 7542 participants, 83 experienced a myocardial infarct during the course of the study. Multivariate logistic regression analysis revealed that vector cardiogram (VCG) measurements provide significant additional information to risk estimation which is equivalent to that of other risk factors. Measurement changes are stronger risk indicators than single measurements. The results confirm previous findings from H.V. Pipbe…