Mostrando recursos 1 - 20 de 508

  1. José Martís Denken über Wirtschaft

    Andiel, Herta; Cayuelas Franco, Carmen
    José Martí (1853-1895) is well known as the spiritual leader of Cuban independence and revolution. The famous writer and intellectual has left a rich legacy of political commentaries, speeches, poems and letters. Many of these texts have been published in both, North and South America. This article examines José Martí's reflections on economic matters and dwells on the economic relevance of his political writings. His texts are contextualised in the specific Latin American conjuncture at the end of 19th century. From this point of view some of his most important texts have to be understood as political interventions in favour...

  2. Product Differentiation or Spatial Monopoly? The Market Areas of Austrian Universities in Business Education.

    Maier, Gunther
    Series: SRE - Discussion Papers

  3. Clusterentwicklung und -politik im Biotechnologiesektor Wien im Kontext internationaler Erfahrungen

    Tödtling, Franz; Trippl, Michaela; Gabain, Joshua von
    (kein Autorenref. vorhanden)

  4. Object-oriented Computation of Sandwich Estimators

    Zeileis, Achim
    Sandwich covariance matrix estimators are a popular tool in applied regression modeling for performing inference that is robust to certain types of model misspecification. Suitable implementations are available in the R system for statistical computing for certain model fitting functions only (in particular lm()), but not for other standard regression functions, such as glm(), nls(), or survreg(). Therefore, conceptual tools and their translation to computational tools in the package sandwich are discussed, enabling the computation of sandwich estimators in general parametric models. Object orientation can be achieved by providing a few extractor functions-most importantly for the empirical estimating functions-from which...

  5. Object-oriented Computation of Sandwich Estimators

    Zeileis, Achim
    Sandwich covariance matrix estimators are a popular tool in applied regression modeling for performing inference that is robust to certain types of model misspecification. Suitable implementations are available in the R system for statistical computing for certain model fitting functions only (in particular lm()), but not for other standard regression functions, such as glm(), nls(), or survreg(). Therefore, conceptual tools and their translation to computational tools in the package sandwich are discussed, enabling the computation of sandwich estimators in general parametric models. Object orientation can be achieved by providing a few extractor functions-most importantly for the empirical estimating functions-from which...

  6. A strategic investment game with endogenous absorptive capacity

    Hammerschmidt, Anna
    R&D plays a dual role: First, it generates new knowledge and second, it develops a firm's absorptive capacity. Most of the existing strategic investment game models neglect, however, the second role of R&D. The aim of this paper is to incorporate the absorptive capacity hypothesis in such a model by endogenizing the spillover. A two-stage game is established and subsequently solved, looking for the subgame perfect Nash equilibria. Considering the comparative static properties of the model as well as the simulation results, a new effect appears: The "free-rider effect" of the models with exogenous spillover, which deteriorates the higher the...

  7. Largest Eigenvalues of Degree Sequences

    Biyikoglu, Türker; Leydold, Josef
    We show that amongst all trees with a given degree sequence it is a ball where the vertex degrees decrease with increasing distance from its center that maximizes the spectral radius of the graph (i.e., its adjacency matrix). The resulting Perron vector is decreasing on every path starting from the center of this ball. This result it also connected to Faber-Krahn like theorems for Dirichlet matrices on trees. The above result is extended to connected graphs with given degree sequence. Here we give a necessary condition for a graph that has greatest maximum eigenvalue. Moreover, we show that the greatest...

  8. A Note on the Folding Coupler

    Hörmann, Wolfgang; Leydold, Josef
    Perfect Gibbs sampling is a method to turn Markov Chain Monte Carlo (MCMC) samplers into exact generators for independent random vectors. We show that a perfect Gibbs sampling algorithm suggested in the literature is not always generating from the correct distribution. (author's abstract)

  9. Musikwirtschaft und neue Medien. Veränderungen in der Musikwirtschaft durch die Digitalisierung aus der Sicht von österreichischen Musikexperten und Vertretern der Musikwirtschaft.

    Ehrenhöfer, Katrin; Koppensteiner, Gudrun; Pumberger, Doris; Steinbauer, Birgit
    In dieser Forschungsarbeit geht es um den Umbruch, den der österreichische Musikmarkt in den letzten Jahren durch die Digitalisierung (Stichwort "MP3") erlebt hat und dessen Auswirkungen: Durch die Entkopplung der Musik von ihrem bisherigen Tonträger wurde es möglich, diese weltweit über große Distanzen zu transportieren (Stichwort "Peer-to-Peer- Netzwerke"). Für die Musikindustrie bedeutete dies bisher einerseits massive Einbrüche in Umsatz und Gewinn, andererseits entstehen durch effizientere weltweite Distribution und Kosteneinsparungen auch neue Chancen. Somit wird es in der Wertschöpfungskette voraussichtlich starke Veränderungen geben: Die Bedeutung der Distribution und der Produktion wird sich zugunsten von Marketing und dem Entdecken von Musikern (A&R)...

  10. Kinderkonzerte als Mittel der Distinktion. Soziologische Betrachtung von Kinderkonzerten in Wien anhand von Pierre Bourdieus kultursoziologischem Ansatz.

    Aicher, Linda
    Based on qualitative interviews, this paper explores how classical children's concerts serve as a means of "social distinction" (Bourdieu) for upper class families. Firstly, the paper presents a description of Vienna's children's concert scene for classical music and elaborates on Bourdieu's cultural-sociological approach. Secondly, the interrelation between knowledge about music and the accumulation of cultural capital, which emphasizes an individual's position in social space (Bourdieu), is investigated. The empirical data show that only children whose parents possess relatively high amounts of cultural and economic capital attend children's concerts. By taking their children to those cultural events, parents not only aim...

  11. Text Clustering with String Kernels in R

    Karatzoglou, Alexandros; Feinerer, Ingo
    We present a package which provides a general framework, including tools and algorithms, for text mining in R using the S4 class system. Using this package and the kernlab R package we explore the use of kernel methods for clustering (e.g., kernel k-means and spectral clustering) on a set of text documents, using string kernels. We compare these methods to a more traditional clustering technique like k-means on a bag of word representation of the text and evaluate the viability of kernel-based methods as a text clustering technique. (author's abstract)

  12. Deriving Consensus Rankings from Benchmarking Experiments

    Hornik, Kurt; Meyer, David
    Whereas benchmarking experiments are very frequently used to investigate the performance of statistical or machine learning algorithms for supervised and unsupervised learning tasks, overall analyses of such experiments are typically only carried out on a heuristic basis, if at all. We suggest to determine winners, and more generally, to derive a consensus ranking of the algorithms, as the linear order on the algorithms which minimizes average symmetric distance (Kemeny-Snell distance) to the performance relations on the individual benchmark data sets. This leads to binary programming problems which can typically be solved reasonably efficiently. We apply the approach to a medium-scale...

  13. Deriving Consensus Rankings from Benchmarking Experiments

    Hornik, Kurt; Meyer, David
    Whereas benchmarking experiments are very frequently used to investigate the performance of statistical or machine learning algorithms for supervised and unsupervised learning tasks, overall analyses of such experiments are typically only carried out on a heuristic basis, if at all. We suggest to determine winners, and more generally, to derive a consensus ranking of the algorithms, as the linear order on the algorithms which minimizes average symmetric distance (Kemeny-Snell distance) to the performance relations on the individual benchmark data sets. This leads to binary programming problems which can typically be solved reasonably efficiently. We apply the approach to a medium-scale...

  14. Evaluating Model-based Trees in Practice

    Zeileis, Achim; Hothorn, Torsten; Hornik, Kurt
    A recently suggested algorithm for recursive partitioning of statistical models (Zeileis, Hothorn and Hornik, 2005), such as models estimated by maximum likelihood or least squares, is evaluated in practice. The general algorithm is applied to linear regression, logisitic regression and survival regression and applied to economical and medical regression problems. Furthermore, its performance with respect to prediction quality and model complexity is compared in a benchmark study with a large collection of other tree-based algorithms showing that the algorithm yields interpretable trees, competitive with previously suggested approaches. (author's abstract)

  15. Evaluating Model-based Trees in Practice

    Zeileis, Achim; Hothorn, Torsten; Hornik, Kurt
    A recently suggested algorithm for recursive partitioning of statistical models (Zeileis, Hothorn and Hornik, 2005), such as models estimated by maximum likelihood or least squares, is evaluated in practice. The general algorithm is applied to linear regression, logisitic regression and survival regression and applied to economical and medical regression problems. Furthermore, its performance with respect to prediction quality and model complexity is compared in a benchmark study with a large collection of other tree-based algorithms showing that the algorithm yields interpretable trees, competitive with previously suggested approaches.

  16. Bayesian Variable Selection for Logistic Models Using Auxiliary Mixture Sampling

    Tüchler, Regina
    The paper presents an Markov Chain Monte Carlo algorithm for both variable and covariance selection in the context of logistic mixed effects models. This algorithm allows us to sample solely from standard densities, with no additional tuning being needed. We apply a stochastic search variable approach to select explanatory variables as well as to determine the structure of the random effects covariance matrix. For logistic mixed effects models prior determination of explanatory variables and random effects is no longer prerequisite since the definite structure is chosen in a data-driven manner in the course of the modeling procedure. As an illustration...

  17. On the Asymptotic Theory of Permutation Statistics

    Strasser, Helmut; Weber, Christian
    In this paper limit theorems for the conditional distributions of linear test statistics are proved. The assertions are conditioned by the sigma-field of permutation symmetric sets. Limit theorems are proved both for the conditional distributions under the hypothesis of randomness and under general contiguous alternatives with independent but not identically distributed observations. The proofs are based on results on limit theorems for exchangeable random variables by Strasser and Weber. The limit theorems under contiguous alternatives are consequences of an LAN-result for likelihood ratios of symmetrized product measures. The results of the paper have implications for statistical applications. By example it...

  18. On a Lemma of Schachermayr

    Strasser, Helmut
    In this paper we prove a topological lemma on real valued random variables which implies the basic ingredients for the proof of the Fundamental Theorem of Asset Pricing in the two period case. In particular, previous results of Stricker and of Schachermayer are special cases of our result. Our proof is considerably shorter and more transparent than previous proofs of related special cases.

  19. Policy agents as catalysts of knowledge links in the biotechnology sector

    Trippl, Michaela; Gabain, Joshua von; Tödtling, Franz
    The purpose of this paper is to explore the role of public policy in promoting interorganisational knowledge links in the biotechnology sector. Despite the significance of such interactions and the policy efforts devoted to them, there is a limited understanding of how different initiatives from various policy levels contribute to the formation of specific knowledge linkages within the biotechnology industry. The paper identifies four main types of knowledge exchange, including market relations, spillovers, formal co-operations and informal networking. Drawing on evidence from the Vienna biotechnology cluster we intend to show how national and regional policy programmes and government actions function...

  20. Die Wiener Indie-Szene. Independent Networking innerhalb einer verworrenen Mikroökonomie.

    Cserer, Michael; Paukovits, Harald; Teodorowicz, Slawomir; Wolf, Thomas
    Based on qualitative interviews with musicians, label owners, owners of clubs and journalists, this paper describes Vienna's independent music scene from different angles. Beside of the pure description of the field of creative production (Bourdieu), we focus on the economic aspects of the scene and the relationships between the members of the scene. We show that the music production within the scene does not follow the rules of the market. It is neither organized within hierarchies, but mostly works on the basis of informal exchange. This works because the scene members are motivated intrinsically. So the artistic expression, high quality...

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