Contributions in Merlin

Issue tracking repositories contain a wealth of information for reasoning about various aspects of software development processes. In this paper, we focus on bug triaging and provide visual means to explore the effort estimation quality and the bug life-cycle of reported problems. Our approach follows the Micro/Macro reading technique and uses a combination of graphical views to investigate details of individual problem reports while maintaining the context provided by the surrounding data population. This enables the detection and detailed analysis of hidden pat- terns and facilitates the analysis of problem report outliers. In an industrial study, we use our approach in various problem report analysis scenarios and answer questions related to effort estimation and resource planning.

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In this paper I employ a dynamic general equilibrium model to study macroeconomic effects and welfare implications of alternative reforms to the U.S. health insurance system. In particular, I focus on expanding Medicare to the entire population, extending Medicaid, and having an individual mandate as well as other related medical reforms. All these reforms can be financed in several ways. I consider a stochastic OLG framework with heterogeneous agents facing uncertain health shocks. Individuals make optimal decisions on labor supply, health insurance, and medical services. As the amount of optimal medical consumption and hours worked are endogenous, this environment captures general equilibrium effects. The model is calibrated to the U.S. data. Numerical simulations indicate that reforming the health insurance system has several important macroeconomic effects on health expenditures, hours worked, and welfare.

For quite some years now, there has been a growing debate under the label of “Green I(C)T” about reducing the en-ergy consumption of ICT equipment. More recently, the discourse started to partly shift towards a novel discussion on using ICT to induce energy savings in sectors other than ICT. Advocates suggest that the cumulated potential for ICT-induced savings is several times larger than the entire energy consumption of ICT itself. Numerous studies on ICT-related energy consumption exist, and also an increasing number of studies looking at ICT-induced energy efficiency. The few studies, however, considering both aspects, typically do so independently, without relating the two aspects. Moreover, in the energy efficiency discourse, ICT is usually treated as a monolithic block of technologies – only the application areas that are expected to benefit from it being differentiated. In this paper, we make the case that ICT energy consumption and ICT’s potential for inducing energy efficiency can – and should – be related to each other. We further argue that this can only be obtained by decomposing the “ICT monolith” and look at its (naturally heterogeneous) parts separately. Based on a first round of expert interviews, we show that it is possible to qualitatively determine for every single technology subsumed under ICT its potential for inducing energy efficiency. We finally argue that only by consequently following low energy consumption targets for technologies with a low energy efficiency potential, while at the same time not suffocating technologies with a high energy efficiency potential through restrictive consumption targets, the full ICT-related energy saving potential can be unleashed.

We present a methodology to extract the backbone of complex networks based on the weight and direction of links, as well as on nontopological properties of nodes. We show how the methodology can be applied in general to networks in which mass or energy is flowing along the links. In particular, the procedure enables us to address important questions in economics, namely, how control and wealth are structured and concentrated across national markets. We report on the first cross-country investigation of ownership networks, focusing on the stock markets of 48 countries around the world. On the one hand, our analysis confirms results expected on the basis of the literature on corporate control, namely, that in Anglo-Saxon countries control tends to be dispersed among numerous shareholders. On the other hand, it also reveals that in the same countries, control is found to be highly concentrated at the global level, namely, lying in the hands of very few important shareholders. Interestingly, the exact opposite is observed for European countries. These results have previously not been reported as they are not observable without the kind of network analysis developed here.

In this paper we present a recursive method for the computation of dynamic competitive equilibria in models with heterogeneous agents and market frictions. This method is based on a convergent operator over an expanded set of state variables. The fixed point of this operator defines the set of all Markovian equilibria. We study approximation properties of the operator as well as the convergence of the moments of simulated sample paths. We apply our numerical algorithm to two growth models, an overlapping generations economy with money, and an asset pricing model with financial frictions.

The recent credit crisis and the increased internationalization of the European banks have given the debate about the role of national regulators a renewed urgency. We therefore investigate the determinants of bondholders’ abnormal returns for both domestic and cross-border bank merger announcements that involve European acquirers for the period 1998–2002. We find that bondholders’ abnormal returns are higher for Domestic Mergers than cross-border mergers, in direct contrast to evidence from equity prices where no difference is found. Further investigations in which we control for the changes in market power for example suggest this result may be indicative of investors perceiving Domestic Mergers as increasing the probability of a government bailout in case of distress. Banks’ bondholders also experience higher abnormal returns when the country of the partner bank has stricter rules in relation to forbearance of prudential regulations than the own country, and when functional diversification between lending and fee/trading activities increases.

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