Search results for "methodology."

On the sign recovery by LASSO, thresholded LASSO and thresholded Basis Pursuit Denoising

2020

Basis Pursuit (BP), Basis Pursuit DeNoising (BPDN), and LASSO are popular methods for identifyingimportant predictors in the high-dimensional linear regression model Y = Xβ + ε. By definition, whenε = 0, BP uniquely recovers β when Xβ = Xb and β different than b implies L1 norm of β is smaller than the L1 norm of b (identifiability condition). Furthermore, LASSO can recover the sign of β only under a much stronger irrepresentability condition. Meanwhile, it is known that the model selection properties of LASSO can be improved by hard-thresholdingits estimates. This article supports these findings by proving that thresholded LASSO, thresholded BPDNand thresholded BP recover the sign of β in …

Purification of recovered phosphoric acid by extracting aluminium with di-2-ethylhexyl phosphoric acid

2021

AbstractThe extraction of aluminium from dilute phosphoric acid with di-2-ethylhexyl phosphoric acid (DEHPA) was optimized using response surface methodology. The optimization was based on the experimental three-level central composite face-centred design (CCF) and was conducted on real-life samples. The three variables included were pH, extractant concentration and aqueous to organic phase ratio (AO). Under the optimized conditions (pH 2.5, 0.6 M DEHPA and AO ratio 1:2), extraction efficiency of 99% for aluminium in four extraction stages is achieved. The purified phosphoric acid solution can then be utilized by the fertilizing industry. Stripping tests for organic phase loaded with alumin…

First morphogenetic analysis of parasite eggs from Schistosomiasis haematobium infected sub-Saharan migrants in Spain and proposal for a new standard…

2021

International audience; Schistosomiasis is a Neglected Tropical Disease caused by trematode species of the genus Schistosoma. Both, autochthonous and imported cases of urogenital schistosomiasis have been described in Europe. The present study focuses on eggs, considered pure S. haematobium by genetic characterisation (intergenic ITS region of the rDNA and cox1 mtDNA). A phenotypic characterisation of S. haematobium eggs was made by morphometric comparison with experimental populations of S. bovis and S. mansoni, to help in the diagnosis of S. haematobium populations infecting sub-Saharan migrants in Spain. Analyses were made by Computer Image Analysis System (CIAS) applied on the basis of …

Subjectivation, togetherness, environment. Potentials of participatory art for Art Education for Sustainable Development (AESD)

2017

Through a process-oriented analysis of the participatory art project The Hill this article explores the relevance of participatory art projects for the development of AESD – Art Education for Sustainable Development. Inspired by Felix Guattari’s Three Ecologies (2008) the analysis moves through three sub-studies delving into three different aspects of the project. Each sub-study adopts two overlapping analytical ‘lenses’: The lens of a contemporary art form (performance art, community art, and site-specific art) and the lens of a related theoretical concept (subjectivation, togetherness, environment). The aim is to propose art educational ideas and strategies that stimulate students to chal…

Improving predictive accuracy of exit polls

2010

Abstract Exit polls are best known for their use in election forecasting. In recent years, however, some prominent mistaken predictions have been made, undermining public confidence in the accuracy of both exit polls and survey methods. Nonresponse bias has been claimed as being one of the main reasons for inaccurate projections. Traditionally, the issue has been handled through an age–race–sex adjustment at the national and state levels. An alternative solution is suggested and detailed in this paper. A two-step strategy is proposed to reduce nonresponse bias and improve predictions. First, “vote-remembering” (vote recall) is used to correct party proportion estimates at polling locations;…

Media Effects: Levels of Analysis

2017

AN EMPIRICAL STUDY OF LATVIAN CONSUMER’S ATTITUDES AND PERCEPTIONS TOWARDS GENETICALLY MODIFIED ORGANISMS

2016

Genetic modification and genetically modified organisms (GMO) remains a controversial issue. Latvian consumers’ attitude towards genetic modification and GMO have been characterized as negative using Eurobarometer data, but so far no specific investigation of Latvian consumers has been done in this field. The aim of this study was to analyse Latvian consumers’ attitude towards genetic modification and GMO, the subjective and objective knowledge about this questions and acceptability of use of GMO in different application areas. Main task in frame of this research is to summarize different literature and data available to outline some of factors that influence attitudes towards GMO: mainly p…

Insights on integrated marketing communications: implementation and impact in hotel companies

2015

Purpose – The purpose of this paper is to provide insights on integrated marketing communications (IMC) by empirically examining the concept in a new context, that is hotel companies, and comparing its implementation and impact in Italian and Croatian hotels. Design/methodology/approach – The study uses survey methodology to assess IMC, approaching managers and guests in high-quality hotels. Findings – From the manager’s point of view, both Italian and Croatian hotels show a high level of IMC implementation and significant differences regarding some items. From the guest’s point of view, significant differences are obtained between the two hotel groups. In addition, IMC is found to influen…

A Comparative Expert Survey on Measuring and Enhancing Children and Young People’s Well-Being in Europe

2018

The understanding of children and young peoples’ well-being varies greatly not just between different experts and scholars, but also across countries and cultures, depending on the historical and socio-economic context. However, an effective application of scholarly research to policy-making, especially at the supra-national level, requires establishing a comparable set of indicators that would allow measuring and comparing children and young people’s well-being across countries, over time and in relation to specific policy instruments. This chapter outlines the key findings from a Delphi survey, comprising a panel of 334 European experts in the fields of survey methodology, children and yo…

Semiparametric Models with Functional Responses in a Model Assisted Survey Sampling Setting : Model Assisted Estimation of Electricity Consumption Cu…

2010

This work adopts a survey sampling point of view to estimate the mean curve of large databases of functional data. When storage capacities are limited, selecting, with survey techniques a small fraction of the observations is an interesting alternative to signal compression techniques. We propose here to take account of real or multivariate auxiliary information available at a low cost for the whole population, with semiparametric model assisted approaches, in order to improve the accuracy of Horvitz-Thompson estimators of the mean curve. We first estimate the functional principal components with a design based point of view in order to reduce the dimension of the signals and then propose s…