Search results for "Linear regression"
showing 10 items of 375 documents
Relationship among Corneal Biomechanics, Refractive Error, and Axial Length
2014
Purpose To evaluate the relationship between different ocular and corneal biomechanical parameters in emmetropic and ametropic healthy white children. Methods This study included 293 eyes of 293 healthy Spanish children (135 boys and 158 girls), ranging in age from 6 to 17 years. Subjects were divided according to the refractive error: control (emmetropia, 99 children), myopia (100 children), and hyperopia (94 children) groups. In all cases, corneal hysteresis (CH) and corneal resistance factor (CRF) were evaluated with the Ocular Response Analyzer system. Axial length (AL) and mean corneal power were also measured by partial coherence interferometry (IOLMaster), and central corneal thickne…
Associations of Objectively Measured Physical Activity and Sedentary Time With Arterial Stiffness in Pre-Pubertal Children.
2017
Purpose: To investigate the relationships of objectively measured physical activity (PA) and sedentary time (ST) to arterial stiffness in pre-pubertal children. Method: Altogether 136 children (57 boys, 79 girls) aged 6–8-years participated in the study. Stiffness index (SI) was assessed by pulse contour analysis based on photoplethysmography. ST, light PA, moderate PA, and vigorous PA were assessed using combined acceleration and heart rate monitoring. We investigated the associations of ST (<1.5METs) and time spent in intensity level of PA above 2–7METs in min/d with SI using linear regression analysis. We studied the optimal duration and intensity of PA to identify children being in the …
D-Dimer and thrombus burden in acute pulmonary embolism.
2018
Abstract Background Thrombus burden in pulmonary embolism (PE) is associated with higher D-Dimer-levels and poorer prognosis. We aimed to investigate i) the influence of right ventricular dysfunction (RVD), deep venous thrombosis (DVT), and high-risk PE-status on D-Dimer-levels and ii) effectiveness of D-Dimer to predict RVD in normotensive PE patients. Methods Overall, 161 PE patients were analyzed retrospectively, classified in 5 subgroups of thrombus burden according to clinical indications and compared regarding D-Dimer-levels. Linear regression models were computed to investigate the association between D-Dimer and the groups. In hemodynamically stable PE patients, a ROC curve was calc…
Prediction Accuracy of a Novel Dynamic Structure-Function Model for Glaucoma Progression
2014
Purpose To assess the prediction accuracy of a novel dynamic structure-function (DSF) model to monitor glaucoma progression. Methods Longitudinal data of paired rim area (RA) and mean sensitivity (MS) from 220 eyes with ocular hypertension or primary open-angle glaucoma enrolled in the Diagnostic Innovations in Glaucoma Study or the African Descent and Glaucoma Evaluation Study were included. Rim area and MS were expressed as percent of mean normal based on an independent dataset of 91 healthy eyes. The DSF model uses centroids as estimates of the current state of the disease and velocity vectors as estimates of direction and rate of change over time. The first three visits were used to pre…
An elevated body mass index increases lung volume but reduces airflow in italian schoolchildren
2013
Background Asthma and obesity are important and growing health issues worldwide. Obesity is considered a risk factor for asthma, due to the induction of changes in airway mechanics and altered airway inflammation. Methods We cross-sectionally investigated the effect of increased weight on pulmonary function in a large population sample of healthy children, aged 10–17 yrs living in Palermo, Italy. Explanatory effect of weight on lung function variables were evaluated by multiple linear regression models, taking into account height, gender, and age-class. Results Among the 2,393 subjects, FVC and FEV1 were positively correlated to weight. Multiple regression models showed that the weight beta…
Longitudinal Associations of Fitness, Motor Competence, and Adiposity with Cognition
2019
Purpose: The purpose of this study was to investigate the longitudinal associations of cardiorespiratory fitness (CRF), motor competence (MC), and body fat percentage (BF%) with cognition in children. Methods: Altogether, 371 children (188 boys and 183 girls) 6–9 yr of age at baseline participated in this 2-yr follow-up study. We assessed CRF by maximal cycle ergometer test, computed the MC score from the z-scores of the 50-m shuttle run, static balance, and box and block test results, measured BF% by dual-energy x-ray absorptiometry, and assessed cognition using the Raven’s Coloured Progressive Matrices (RCPM) score. The associations were studied by linear regression analysis and repeated-…
ANÁLISIS DEL COMPORTAMIENTO DE QUEJA DEL CONSUMIDOR: UNA INVESTIGACIÓN EXPLORATORIA EN EL CONTEXTO DE LOS RESTAURANTES /
2008
RESUMENEl objetivo de este trabajo es analizar la contribución que tiene una serie de determinantes en el comportamiento de queja con el fin de identificar la combinación que mejor explica las respuestas de queja, a terceras partes y privadas. Utilizando el contexto de los restaurantes y la metodología basada en modelos de regresión múltiple (método secuencial de estimación paso a paso), los resultados más relevantes indican que la probabilidad de éxito de la queja es la variable que mayor influencia tiene sobre las respuestas de queja, mientras que es el nivel de insatisfacción en el caso de las respuestas privadas.ABSTRACTThe aim of this paper is to analyze the contribution that a set of …
A novel application of fuzzy-set qualitative comparative analysis to GEM data
2016
Abstract This study constitutes a novel application of fuzzy-set qualitative comparative analysis to Global Entrepreneurship Monitor (GEM) data. This study seeks to demonstrate that fsQCA enriches previous conclusions from linear regression analyses that state that a relationship exists between the GEM's Total Entrepreneurial Activity rate (TEA) and variables representing entrepreneurial attitudes and social values of adult populations toward entrepreneurship. FsQCA allows researchers to estimate which of these attitudes and social values are necessary, sufficient, or both for full membership in the set of most entrepreneurial active countries within the set of GEM innovation-driven countri…
Get into flow: Design of experiments as a key technique in the optimization of anodic dehydrogenative C,C cross-coupling reaction of phenols in flow …
2021
Abstract The optimization of electro-organic reactions poses a challenge due to the various parameters involved. Quite often those parameters are not independent from each other, leading the experimental scientist using linear approaches into an optimization loophole. We report a strategy for the optimization of the anodic oxidative dehydrogenative C,C cross-coupling reactions for the synthesis of biphenols based on Design of Experiments (DoE), which overcomes the drawbacks of linear optimization approaches. Using a fractional design, we increased the yield of a long-time investigated example reaction from 44% up to 85% and point out different suitable reaction conditions through to linear …
Testing the concentric-disk tension infiltrometer for field measurement of soil hydraulic conductivity
2010
Abstract The concentric-disk tension infiltrometer (CDTI) may be used to simultaneously measure the confined ( K c ) and the unconfined ( K u ) soil hydraulic conductivity, but it has received little testing. Comparison between K c and K u can be affected by the calculation approach applied to analyze unconfined steady-state infiltration rates. The objectives of this investigation were to: i) establish the effect of the calculation approach on the estimates of K u ; and ii) compare the K c and K u values measured by the CDTI. A clay soil, a structureless sandy loam soil, and a sandy loam soil with a relatively high gravel content were sampled using a disk of radius equal to 107.5 mm, compri…