Search results for "Influence"

Symmetrised M-estimators of multivariate scatter

2007

AbstractIn this paper we introduce a family of symmetrised M-estimators of multivariate scatter. These are defined to be M-estimators only computed on pairwise differences of the observed multivariate data. Symmetrised Huber's M-estimator and Dümbgen's estimator serve as our examples. The influence functions of the symmetrised M-functionals are derived and the limiting distributions of the estimators are discussed in the multivariate elliptical case to consider the robustness and efficiency properties of estimators. The symmetrised M-estimators have the important independence property; they can therefore be used to find the independent components in the independent component analysis (ICA).

k-Step shape estimators based on spatial signs and ranks

2010

In this paper, the shape matrix estimators based on spatial sign and rank vectors are considered. The estimators considered here are slight modifications of the estimators introduced in Dümbgen (1998) and Oja and Randles (2004) and further studied for example in Sirkiä et al. (2009). The shape estimators are computed using pairwise differences of the observed data, therefore there is no need to estimate the location center of the data. When the estimator is based on signs, the use of differences also implies that the estimators have the so called independence property if the estimator, that is used as an initial estimator, has it. The influence functions and limiting distributions of the es…

A gradient-based deletion diagnostic measure for generalized linear mixed models

2016

ABSTRACTA gradient-statistic-based diagnostic measure is developed in the context of the generalized linear mixed models. Its performance is assessed by some real examples and simulation studies, in terms of ability in detecting influential data structures and of concordance with the most used influence measures.

Statistical inference as a decision problem: the choice of sample size

1997

‘You really are a great big sister’ – parasocial relationships, credibility, and the moderating role of audience comments in influencer marketing

2020

This study examines the moderating role of audience comments in influencer marketing. A YouTube vlog entry by a social media influencer featuring the endorsement of a brand was studied, and an experimental design featuring two conditions related to audience comments was created. The results indicate that a parasocial relationship with the influencer builds the perceived credibility of the influencer, while comments by other audience members moderate the effect. Influencer credibility positively affects brand trust and purchase intention. The findings enhance the understanding of the role of an active audience in influencer marketing. peerReviewed

The role of guilt in the willingness to pay : application to purchase for the child and to purchase organic food products

2011

Guilt in marketing is a concept which is mostly analysed by anglo-saxon researchers. French research on this topic is limited. This concept has always been analysed as a persuasion tool or after a purchase. The guilt that could explain a consumer’s purchase doesn’t seem to have been analysed much. The purpose of this thesis deals with the following topic : the role of guilt in the consumer behaviour. We have particulary wondered whether guilt stimulation could increase the willingness to pay.

Understanding adults’ strong problem-solving skills based on PIAAC

2017

Purpose Research has shown that the problem-solving skills of adults with a vocational education and training (VET) background in technology-rich environments (TREs) are often inadequate. However, some adults with a VET background do have sound problem-solving skills. The present study aims to provide insight into the socio-demographic, work-related and everyday life factors that are associated with a strong problem-solving performance. Design/methodology/approach The study builds on large-scale data of the Programme for the International Assessment of Adult Competencies (PIAAC) and gives insight into VET adults (N = 12,929) with strong problem-solving skills in 11 European countries. Find…

Assessing the territorial influence of an Iberian worship site. The chemical characterisation of the terracotta from the Iron Age sanctuary of La Ser…

2017

This paper presents the study of the prestigious terracotta votive figurines from the Iberian Iron Age sanctuary of La Serreta (Alicante province, Spain) composed of 174 items. Portable X-ray fluorescence (PXRF) was used to identify elemental markers that permit us to observe the differences between local and non-local terracotta figurines and furthermore to evaluate the geographical influence of the La Serreta sanctuary using Principal Component Analysis (PCA). The Partial Least Squares Discriminant Analysis (PLSDA) statistical method was also used to classify the figurines of uncertain geographical origin. The resulting groups were related to typological and stylistic groups of figurines …

Non-Linear Hysteretic Instability in Rotating Machinery

2013

L'intonaco Li Vigni nell'architettura del XX secolo a Palermo. Nuove conoscenze e applicazioni diagnostiche per la manutenzione

2013

Il saggio presenta lo studio degli intonaci formulati per imitare le pietre e i marmi naturali che si diffondono in Sicilia all’inizio del XX secolo ed evidenzia che le prime applicazioni e la diffusione delle nuove malte, anche nel resto dell’Italia, risentono delle sperimentazioni condotte in tutta l’Europa. Il contributo riassume i risultati di una rigorosa e capillare ricognizione tra i brevetti conservati presso l’Archivio Centrale dello Stato a Roma inerenti alle malte per il confezionamento dell’intonaco a “finta pietra”, ne analizza i contenuti in modo critico e pone in risalto i contatti culturali con le sperimentazioni dei materiali in atto nell’ambito dei grandi cantieri di resta…