Search results for " statistics"
showing 10 items of 1891 documents
Morphostatistical characterization of the spatial galaxy distribution through Gibbs point processes
2021
This paper proposes a morpho-statistical characterisation of the galaxy distribution through spatial statistical modelling based on inhomogeneous Gibbs point processes. The galaxy distribution is supposed to exhibit two components. The first one is related to the major geometrical features exhibited by the observed galaxy field, here, its corresponding filamentary pattern. The second one is related to the interactions exhibited by the galaxies. Gibbs point processes are statistical models able to integrate these two aspects in a probability density, controlled by some parameters. Several such models are fitted to real observational data via the ABC Shadow algorithm. This algorithm provides …
Counseling Patients with a Glioblastoma Amenable Only for Subtotal Resection: Results of a Multicenter Retrospective Assessment of Survival and Neuro…
2017
Background Patients with a glioblastoma (GB) amenable only for subtotal resection (STR) represent a challenge in patient counseling. Our objective was to assess impact of extent of resection (EoR) on survival and clinical outcome of these patients. Methods We performed a retrospective multicenter assessment. Patients receiving an intended STR in 3 centers with unilocular, primary, highly eloquent GB who received the same adjuvant treatment were included. We assessed EoR, neurologic outcome, and rate of complications. Progression-free survival (PFS) and overall survival (OS) were calculated with Kaplan–Meier estimations. We used 1% EoR and 1-cm3 steps to detect a threshold for a minimal EoR …
Causal Inference and Statistical Fallacies
2001
Fallacies are defined as plausible-seeming arguments that give the wrong conclusion. The article concentrates on those with some connection with causality. The classical definition of causality involving a necessary and sufficient condition for an effect is rejected and three possible definitions discussed. The first is that of a statistical association that cannot be explained away as the effect of admissible alternative features. To make this more precise, Markov graphical representations are introduced and the important distinction between pairs of variables on an equal footing and those in a potential explanatory-response relation described. The roles of unobserved confounders and of ra…
Measuring Spatiotemporal Dependencies in Bivariate Temporal Random Sets with Applications to Cell Biology
2008
Analyzing spatiotemporal dependencies between different types of events is highly relevant to many biological phenomena (e.g., signaling and trafficking), especially as advances in probes and microscopy have facilitated the imaging of dynamic processes in living cells. For many types of events, the segmented areas can overlap spatially and temporally, forming random clumps. In this paper, we model the binary image sequences of two different event types as a realization of a bivariate temporal random set and propose a nonparametric approach to quantify spatial and spatiotemporal interrelations using the pair correlation, cross-covariance, and the Ripley K functions. Based on these summary st…
Applying univariate vs. multivariate statistics to investigate therapeutic efficacy in (pre)clinical trials: A Monte Carlo simulation study on the ex…
2020
BackgroundSmall sample sizes combined with multiple correlated endpoints pose a major challenge in the statistical analysis of preclinical neurotrauma studies. The standard approach of applying univariate tests on individual response variables has the advantage of simplicity of interpretation, but it fails to account for the covariance/correlation in the data. In contrast, multivariate statistical techniques might more adequately capture the multi-dimensional pathophysiological pattern of neurotrauma and therefore provide increased sensitivity to detect treatment effects.ResultsWe systematically evaluated the performance of univariate ANOVA, Welch's ANOVA and linear mixed effects models ver…
Non-specific bronchial hyper-responsiveness in children with allergic rhinitis: relationship with the atopic status
2003
An increased prevalence of bronchial hyper-responsiveness (BHR) has been demonstrated in children from a general population, and in non-asthmatic adults with allergic rhinitis. Thus, also children with allergic rhinitis are expected to be at higher risk of BHR. We evaluated the prevalence of BHR in a sample of non-asthmatic children with allergic rhinitis by means of the methacholine (Mch) bronchial challenge, and by monitorizing the airway patency using the daily peak expiratory flow variability (PEFv). Fifty-one children (ranged 6-15 years of age) with allergic rhinitis, ascertained by skin prick test to inhalant allergens, underwent a 14-day peak expiratory flow monitoring, and a Mch bro…
Biaxial deformation and ductility domains for engineered rectangular RC cross-sections: A parametric study highlighting the positive roles of axial l…
2016
Abstract Axial load and biaxial bending strongly influence the deformation capacity of column cross-sections, in most cases causing a non-negligible loss of curvature and ductility with respect to the case of pure bending along principal axes, commonly assumed as the basic condition to assess the inelastic capacity. In consideration of this the paper investigates the biaxial deformation performance of RC rectangular cross-sections belonging to one-dimensional elements, focusing on the influence of some parameters as the cross-section aspect ratio and the distribution of the rebars, as well as the mechanical characteristics of concrete and steel and the impact of biaxial/axial stresses. In t…
A study of the potential influence of frame coolant distribution on the radiation-induced damage of HCLL-TBM structural material
2008
Abstract Within the European Fusion Technology Programme, the Helium-Cooled Lithium Lead (HCLL) breeding blanket concept is one of the two EU lines to be developed for a Long Term fusion reactor, in particular with the aim of manufacturing a Test Blanket Module (TBM) to be implemented in ITER. The HCLL-TBM is foreseen to be located in an ITER equatorial port, being housed inside a steel-supporting frame, actively cooled by pressurized water. That supporting frame has been designed to house two different TBMs, providing two cavities separated by a dividing Plate 20 cm thick. As the nuclear response of HCLL-TBM might vary accordingly to the supporting frame configuration and composition, at t…
Money Invested on Shopping Online and Payment Methods Used: Findings by Recent Survey
2021
Within development of telecommunication, e-commerce is rapidly replacing traditional shopping as well as offering new ways to pay for goods. Payment is one of the main phases of buying decision process and it is crucial to e-commerce, because there is a big possibility that consumer will abandon the shopping cart if preferred payment method is not available. Not only flexible payment options can help company to attract and retain customers, but it also can ensure that company get paid more quickly. The aim of the research is to find out how much money Latvian customers invest when shopping online and which payment methods they use to pay for the purchase on internet in Latvia. Research meth…
Teachers’ initial training in cultural diversity in Spain: attitudes and pedagogical strategies
2005
This paper examines a number of issues relating to educational responsibility for increasing social cohesion and preventing the segregation of people from different cultures who have to pass through the Spanish educational system. Using a descriptive analysis, we review the present situation. Our review shows that the treatment of cultural diversity by Spanish universities is, in general, insufficient with respect to the training needs that students will demand from the educational system both now and in the future. Simply taking a single course on intercultural issues is not enough to prepare teachers to cope with cultural diversity in the school and classroom. Therefore, educational appro…