607 research outputs found
Robust sparse principal component analysis.
A method for principal component analysis is proposed that is sparse and robust at the same time. The sparsity delivers principal components that have loadings on a small number of variables, making them easier to interpret. The robustness makes the analysis resistant to outlying observations. The principal components correspond to directions that maximize a robust measure of the variance, with an additional penalty term to take sparseness into account. We propose an algorithm to compute the sparse and robust principal components. The method is applied on several real data examples, and diagnostic plots for detecting outliers and for selecting the degree of sparsity are provided. A simulation experiment studies the loss in statistical efficiency by requiring both robustness and sparsity.Dispersion measure; Projection-pursuit; Outliers; Variable selection;
ConsideraçÔes sobre o texto de Christophe Pons: âOcultismo e Protestantismo na IslĂąndia: TendĂȘncias iconĂłfilas de contextos nĂŁo-icĂŽnicosâ
Reação ao texto principal de Christophe Pons. [Tradução: Felipe Gustavo Koch Buttelli
ErwĂ€gungen zu Christophe Pons âOcultismo e Protestantismo na IslĂąndia: TendĂȘncias iconĂłfilas de contextos nĂŁo-icĂŽnicosâ
Reação ao texto principal de Christophe Pon
Dialogues and Dynamics â Interculturality in Theology and Religious Studies
This volume contains the texts from the symposium on the occasion of the 10th Anniversary of the M.A. Programme Intercultural Theology. The contributions address the challenges and consequences of an intercultural approach in academics as well as in the churches and in society. Since globalisation has significantly changed the face of contemporary Christianity in the 21st century, the task of doing theology has become more complex. The cultural, geographic and denominational varieties of Christianity worldwide challenge the traditional Western face of academic Christian theology and demand new and global forms of theological thinking across lines. Intercultural Theology seeks to embrace these dynamics with a constructive dialogue, opening up new spaces of collaborative thinking and academic reflection
tclust: An R Package for a Trimming Approach to Cluster Analysis
Outlying data can heavily influence standard clustering methods. At the same time, clustering principles can be useful when robustifying statistical procedures. These two reasons motivate the development of feasible robust model-based clustering approaches. With this in mind, an R package for performing non-hierarchical robust clustering, called tclust, is presented here. Instead of trying to âfitâ noisy data, a proportion α of the most outlying observations is trimmed. The tclust package efficiently handles different cluster scatter constraints. Graphical exploratory tools are also provided to help the user make sensible choices for the trimming proportion as well as the number of clusters to search for
Robust constrained fuzzy clustering
It is well-known that outliers and noisy data can be very harmful when applying
clustering methods. Several fuzzy clustering methods which are able
to handle the presence of noise have been proposed. In this work, we propose
a robust clustering approach called F-TCLUST based on an âimpartialâ
(i.e., self-determined by data) trimming. The proposed approach considers
an eigenvalue ratio constraint that makes it a mathematically well-defined
problem and serves to control the allowed differences among cluster scatters.
A computationally feasible algorithm is proposed for its practical implementation.
Some guidelines about how to choose the parameters controlling the
performance of the fuzzy clustering procedure are also given.EstadĂstica e I
A fast algorithm for robust constrained clustering
The application of âconcentrationâ steps is the main principle behind Forgyâs
k-means algorithm and Rousseeuw and van Driessenâs fast-MCD algorithm.
Despite this coincidence, it is not completely straightforward to combine both
algorithms for developing a clustering method which is not severely affected
by few outlying observations and being able to cope with non spherical clusters.
A sensible way of combining them relies on controlling the relative cluster
scatters through constrained concentration steps. With this idea in mind,
a new algorithm for the TCLUST robust clustering procedure is proposed
which implements such constrained concentration steps in a computationally
efficient fashion.EstadĂstica e I
Ecumenism as a global player - what moves the world and what moves ecumenic
SchĂ€fer H. Ăkumene als global player - Was bewegt die Welt und was die Ăkumene? In: Erich F, ed. Rekonfiguration. Oder: Die ökumenische Bewegung in Zeiten der Globalisierung. Loccumer Protokoll. Vol 58/04. Rehburg-Loccum.; 2005
Technikfolgen-AbschĂ€tzung zum Raumtransportsystem "SĂNGER"
Kapitel I der Studie enthĂ€lt eine Ăbersicht ĂŒber die heute verfĂŒgbaren Raumtransportsysteme und eine Analyse ihrer Hauptdefizite. Aus dieser Defizitanalyse werden Anforderungen an zukĂŒnftige Raumtransportsysteme abgeleitet. AbschlieĂend werden die wichtigsten derzeit diskutierten Konzepte fĂŒr Raumtransportsysteme der nĂ€chsten Generation" - darunter das Konzept SĂNGER - dargestellt.
In Kapitel II werden Konzeption, Ablauf und Organisation des deutschen Hyperschalltechnologie-Programms und die mit diesem Programm bzw. einem zukĂŒnftigen Raumtransportsystem vom Typ SĂNGER verfolgten Ziele beschrieben. Bei diesen Zielen handelt es sich fast ĂŒberwiegend um "Optimierungsziele" - Raumtransporte sollen in Zukunft z.B. wirtschaftlicher, sicherer, umweltfreundlicher werden -, die den Bedarf nach Raumtransporten und Raumtransportsystemen· voraussetzen.
Der Frage des Bedarfs wird in Kapitel III nachgegangen. Nach einer Darstellung der kontroversen Diskussion um den gesellschaftlichen Nutzen der Raumfahrt und der in dieser Diskussion vertretenen Positionen werden zwei von der DLR in ihrem Gutachten entwickelte raumfahrtpolitische Nutzungsszenarien, beschrieben und diskutiert, insbesondere auch im Hinblick auf darin enthaltene mögliche zukĂŒnftige "Marktsegmente" fĂŒr ein Raumtransportsystem vom Typ SĂNGER.
In Kapitel IV werden die mit dem Hyperschalltechnologie-Programm bzw. einem zukĂŒnftigen System SĂNGER verfolgten Zielsetzungen eingehend analysiert: Reduzierung der Kosten des Raumtransports; Erhöhung der Sicherheit und ZuverlĂ€ssigkeit des Raumtransports; Verbesserung der UmweltvertrĂ€glichkeit des Raumtransports; DurchfĂŒhrung des Raumtransports von europĂ€ischen FlugplĂ€tzen; Verbesserung der technologischen Basis fĂŒr zukĂŒnftige Projekte der Luft- und Raumfahrt sowie fĂŒr andere Gebiete der Hochtechnologie ("Spin-offâ); technologische Vorbereitung der "nĂ€chsten Generation" von Raumtransportsystemen.
In Kapitel V wird - ausgehend von den Ergebnissen der vorangehenden Kapitel - der politische Entscheidungsbedarf bezĂŒglich des Hyperschalltechnologie-Programms und des Leitkonzepts SĂNGER zusammenfassend dargestellt. AbschlieĂend werden politische Handlungsoptionen diskutiert
- âŠ