Mostrando recursos 1 - 10 de 10

  1. movMF: An R Package for Fitting Mixtures of von Mises-Fisher Distributions

    Hornik, Kurt; Grün, Bettina
    Finite mixtures of von Mises-Fisher distributions allow to apply model-based clustering methods to data which is of standardized length, i.e., all data points lie on the unit sphere. The R package movMF contains functionality to draw samples from finite mixtures of von Mises-Fisher distributions and to fit these models using the expectation-maximization algorithm for maximum likelihood estimation. Special features are the possibility to use sparse matrix representations for the input data, different variants of the expectationmaximization algorithm, different methods for determining the concentration parameters in the M-step and to impose constraints on the concentration parameters over the components. In this paper we describe the main fitting...

  2. International Business Cycle Spillovers since the 1870s

    Antonakakis, Nikolaos; Badinger, Harald
    This article considers the evolution of international business cycle interdependencies among 27 developed and developing countries since the beginning of 1870s, utilising the generalized vector autoregressive (VAR)-based spillover index of Diebold and Yilmaz (2012), which allows the construction of a time-varying measure of business cycle spillovers. We find that, on average, 65% of the forecast error variance of the 27 countries' business cycle shocks is due to international spillovers. However, the magnitude of international business cycle spillovers varies considerably over time. There is a clear increasing trend since the end of World War II and until the middle 1980s. After that, international business cycle...

  3. Synergies among Producer Firms, Lead Users, and User Communities: The Case of the LEGO Producer-User Ecosystem

    Hienerth, Christoph; Lettl, Christopher; Keinz, Peter
    While many firms today proactively involve users in their new product development efforts using a wide variety of methods such as the lead user method, firm-hosted user communities, or mass customization toolkits, some pioneering firms are experimenting with the creation of sustainable producer-user ecosystems designed for the continuous exploration and exploitation of business opportunities. In this paper, the functioning of such ecosystems is studied with particular emphasis on the synergies they can yield. Based on an explorative and longitudinal multiple case study design, the producer-user ecosystem of the firm LEGO is analyzed, and three main actors in the ecosystem are identified: entrepreneurial lead users who aim...

  4. Quantifying Structural Attributes of System Decompositions in 28 Feature-oriented Software Product Lines: An Exploratory Study

    Sobernig, Stefan; Apel, Sven; Kolesnikov, Sergiy; Siegmund, Norbert
    Background: A key idea of feature orientation is to decompose a software product line along the features it provides. Feature decomposition is orthogonal to object-oriented decomposition it crosscuts the underlying package and class structure. It has been argued often that feature decomposition improves system structure (reduced coupling, increased cohesion). However, recent empirical findings suggest that this is not necessarily the case, which is the motivation for our empirical investigation. Aim: In fact, there is little empirical evidence on how the alternative decompositions of feature orientation and object orientation compare to each other in terms of their association with observable properties of...

  5. Density Forecasting using Bayesian Global Vector Autoregressions with Common Stochastic Volatility

    Huber, Florian
    This paper puts forward a Bayesian Global Vector Autoregressive Model with Common Stochastic Volatility (B-GVAR-CSV). We assume that Country specific volatility is driven by a single latent stochastic process, which simplifies the analysis and implies significant computational gains. Apart from computational advantages, this is also justified on the ground that the volatility of most macroeconomic quantities considered in our application tends to follow a similar pattern. Furthermore, Minnesota priors are used to introduce shrinkage to cure the curse of dimensionality. Finally, this model is then used to produce predictive densities for a set of macroeconomic aggregates. The dataset employed consists of...

  6. Quantifying Structural Attributes of System Decompositions in 28 Feature-oriented Software Product Lines: An Exploratory Study

    Sobernig, Stefan; Apel, Sven; Kolesnikov, Sergiy; Siegmund, Norbert
    Background: A key idea of feature orientation is to decompose a software product line along the features it provides. Feature decomposition is orthogonal to object-oriented decomposition it crosscuts the underlying package and class structure. It has been argued often that feature decomposition improves system structure (reduced coupling, increased cohesion). However, recent empirical findings suggest that this is not necessarily the case, which is the motivation for our empirical investigation. Aim: In fact, there is little empirical evidence on how the alternative decompositions of feature orientation and object orientation compare to each other in terms of their association with observable properties of...

  7. Quantifying Structural Attributes of System Decompositions in 28 Feature-oriented Software Product Lines: An Exploratory Study

    Sobernig, Stefan; Apel, Sven; Kolesnikov, Sergiy; Siegmund, Norbert
    Background: A key idea of feature orientation is to decompose a software product line along the features it provides. Feature decomposition is orthogonal to object-oriented decomposition it crosscuts the underlying package and class structure. It has been argued often that feature decomposition improves system structure (reduced coupling, increased cohesion). However, recent empirical findings suggest that this is not necessarily the case, which is the motivation for our empirical investigation. Aim: In fact, there is little empirical evidence on how the alternative decompositions of feature orientation and object orientation compare to each other in terms of their association with observable properties of...

  8. Does Elderly Employment have an Impact on Youth Employment? A General Equilibrium Approach

    Stiassny, Alfred; Uhl, Christina
    Does an increase of elderly employment cause a decline in youth employment? A simplified view of a demand driven economy would give a positive answer to this question. Econometric studies based on a single equation approach deliver little support for this belief. However, these studies typically suffer from identification problems to which no attention is paid in most cases. We therefore use a general equilibrium framework when trying to quantify these effects. Using yearly and quarterly Austrian labor and gdp data, we estimate two model variants by Bayesian methods: a) a standard equilibrium model where the degree of complementarity between old,...

  9. Spatial interactions in location decisions: Empirical evidence from a Bayesian spatial probit model

    Nikolic, Adriana; Weiss, Christoph
    In the past few decades spatial econometric models have become a standard tool in empirical research. Nevertheless applications in binary-choice models remain scarce. This paper makes use of Bayesian Spatial Probit Models to model and estimate spatial interactions in location decisions. For this purpose, we focus on the Austrian retail gasoline market, which is going through a process of remarkable structural changes. A short analysis shows that, during the last decade 10.9% of the stations had left the market and a percentage of 29.6% had either left the market or had changed the brand. This paper aims at investigating this...

  10. The Impact of Fiscal Austerity on Suicide: On the Empirics of a Modern Greek Tragedy

    Antonakakis, Nikolaos; Collins, Alan
    Suicide rates in Greece (and other European countries) have been on a remarkable upward trend following the global recession of 2008 and the European sovereign debt crisis of 2009. However, recent investigations of the impact on Greek suicide rates from the 2008 financial crisis have restricted themselves to simple descriptive or correlation analyses. Controlling for various socio-economic effects, this study presents a statistically robust model to explain the influence on realised suicidality of the application of fiscal austerity measures and variations in macroeconomic performance over the period 1968-2011. The responsiveness of suicide to levels of fiscal austerity is established as...

Aviso de cookies: Usamos cookies propias y de terceros para mejorar nuestros servicios, para análisis estadístico y para mostrarle publicidad. Si continua navegando consideramos que acepta su uso en los términos establecidos en la Política de cookies.