Agent-based modelling - A methodology for the analysis of qualitative development processes

The tremendous development of an easy access to computational power within the last 30 years has led to the widespread use of numerical approaches in almost all scientific disciplines. The first generation of simulation models was rather focused on stylized empirical phenomena. With agent-based modelling, however, the trade-off between simplicity in modelling and taking into account the complexity of the socio-economic reality has been enhanced to a large extent. This paper serves as a basic instruction on how to model qualitative change using an agent-based modelling procedure. The necessity to focus on qualitative change is discussed, agent-based modelling is explained and finally an example is given to show the basic simplicity in modelling.agent-based modelling, methodology, evolutionary economics, qualitative change

Observational Comparison of Star Formation in Different Galaxy Types

Galaxies cover a wide range of masses and star formation histories. In this review, I summarize some of the evolutionary key features of common galaxy types. At the high-mass end, very rapid, efficient early star formation is observed, accompanied by strong enrichment and later quiescence, well-described by downsizing scenarios. In the intermediate-mass regime, early-type galaxies may still show activity in low-mass environments or when being rejuvenated by wet mergers. In late-type galaxies, we find continuous, though variable star formation over a Hubble time. In the dwarf regime, a wide range of properties from bursty activity to quiescence is observed. Generally, stochasticity dominates here, and star formation rates and efficiencies tend to be low. Morphological types and their star formation properties correlate with environment.Comment: Invited review to appear in IAU Symposium 270 on "Computational Star Formation". Editors: J. Alves, B.G. Elmegreen, J.M. Girart, and V. Trimble (Cambridge University Press). 12 pages, no figure

An Evolutionary Approach to the Theory of Entrepreneurship

The building blocks of our model are bounded-rational actors with specific sets of endowments: 'entrepreneurial spirit', human capital and venture capital. The entrepreneurial behavior to found a firm is triggered by the individuals' endowments, their social network and the evaluation of the economic situation. Bandwagon effects occur when high growth rates in emerging markets increase firm entries and firm entries in return increase growth rates until competition unfolds its selective power. The firms' survivability is determined by its founders endowments and its competitiveness. If actors are right or wrong in evaluating their economic situation and their consequent decisions is proven ex post. Thus, there will be winners and losers.entrepreneurship, human capital, venture capital, social networks, evolutionary economics, swarms of innovations

Schumpeterian Dynamics and Financial Market Anomalies

In this paper we try to put together both the dynamics of the endogenous evolution of an industry and the corresponding dynamics on the capital market. The first module of our modelling efforts is the endogenous evolution of the industry based on the micro-behaviour of boundedly rational agents. They strive to undertake entrepreneurial actions and found new firms. Thereby, the role of knowledge diffusion is emphasized. The second module, the capital market module, will also be represented by boundedly rational agents. They read the data of the real side of the economy – induced by the real economy module – interact with other investors and eventually derive their investment decisions. The cognitive process will be modelled using a neural network approach.neural networks, financial markets, entrepreneurship, endogenous evolution

Entrepreneurship

The entrepreneur has been neglected over the years in formal economic theorizing. Previously there has been only eclectic theories such as human capital theory and network dynamics which discuss certain perspectives of entrepreneurial behaviour. This insightful book closes this gap in entrepreneurship literature. Inspired by modern physics, author Thomas Grebel brings together an evolutionary methodology, along the way implicating quantum, graph, and percolation theory. Here, Grebel has provided a synthesis of all the main theories of entrepreneurship. Taking an interdisciplinary approach to the subject, this fascinating book opens up new ideas in modelling and the original thinking contained within will be of interest to all those working in the area of business and management as well as those in economics

Diffusion-jump model for the combined Brownian and Neel relaxation dynamics of ferrofluids in the presence of external fields and flow

Relaxation of suspended magnetic nanoparticles occurs via Brownian rotational diffusion of the particle as well as internal magnetization dynamics. The latter is often modeled by the stochastic Landau-Lifshitz equation, but its numerical treatment becomes prohibitively expensive in many practical applications due to a time-scale separation between fast, Larmor-type precession and slow, barrier-crossing dynamics. Here, a diffusion-jump model is proposed to take advantage of the time-scale separation and to approximate barrier-crossings as thermally activated jump processes that occur alongside rotational diffusion. The predictions of our diffusion-jump model are compared to reference results obtained by solving the stochastic Landau-Lifshitz equation coupled to rotational Brownian motion. Good agreement is found in the regime of high energy barriers where Neel relaxation can be considered a thermally activated rare event. While many works in the field have neglected N\'eel relaxation altogether, our approach opens the possibility to efficiently include Neel relaxation also into interacting many-particle models

Allocative efficiency, plant dynamics, and regional productivity: evidence from Germany

This paper argues that regional variation in the efficiency of labor allocation among German manufacturing plants plays a critical role in explaining regional disparities in productivity. In fact, we show that over 50% of the East-West productivity gap is associated with a less efficient labor allocation in former East Germany. Yet, we also demonstrate that the mere focus on East-West comparisons hides partially large differences between the German federal states. These results suggest that regional productivity differences could be substantially narrowed by a more efficient labor allocation among plants. With respect to the underlying causes, we find evidence that the regional differences in allocative efficiency are significantly correlated with differences in export intensity, market concentration and plant size

Endogenous cap reduction in Emission Trading Systems

Since its introduction, the European Emissions Trading Scheme (EU ETS) has been struggling with an oversupply of emission allowances and a highly volatile allowance price. One reason for the price decline is technological progress and ist demand-reducing effect, which is only partially taken into account in the system. We propose a simple benchmark approach to endogenously adjust the supply of allowances to technical progress. Using a non-parametric benchmark approach, we measure the required adjustment of the allowance supply to avoid a technologyinduced price decline and to maintain the incentive to invest in low-carbon technologies

The fallacy in productivity decomposition

This paper argues that the typical practice of performing growth decompositions based on log-transformed productivity values induces fallacious conclusions: using logs may lead to an inaccurate aggregate growth rate, an inaccurate description of the microsources of aggregate growth, or both. We identify the mathematical sources of this log-induced fallacy in decomposition and analytically demonstrate the questionable reliability of log results. Using firm-level data from the French manufacturing sector during the 2009-2018 period, we empirically show that the magnitude of the log-induced distortions is substantial. Depending on the definition of accurate log measures, we find that around 60-80% of four-digit industry results are prone to mismeasurement. We further find significant correlations of this mismeasurement with commonly deployed industry characteristics, indicating, among other things, that less competitive industries are more prone to log distortions. Evidently, these correlations also a affect the validity of studies that investigate the role of industry characteristics in productivity growth

The prices of open access publishing: the composition of APC across different fields of sciences

Modern media technologies paved the way to the open access movement. Instead of the traditional academic subscription and publishing model, which allowed few big publishers to charge excessive publishing fees, the open access model raises the hope for a fair system, where scientific content is freely accessible and thus the dissemination of research work becomes possible at little cost. However, previous literature pointed out that big publishers seem to be able to preserve their market power when going from the subscription-based model to the open access model. In this paper, we take a closer look at the differences across disciplines. The publication routines in Social Sciences, Physical Sciences, Life Sciences and Health Sciences differ to a substantial extent. On these grounds, we test whether there are also differences in the explanations for the article processing charges (APC) across these disciplines. For doing so, we combined various data sources such as the dataset of the “Directory of Open Access”, the “OpenAPC Initiative” and the “CiteScore Metrics”. Our regression results show that the differences across the four fields in terms of publication habits and endowment levels allow publishers to exploit their market power to different extents