Klaus G Troitzsch

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• Prof. Dr.
• Professor Emeritus at University of Koblenz

Assertion of the validity of the way agents' decision-making remains one of the central epistemological problems in empirical agent-based model (ABM) simulations. Reliable and robust models of individual and group-level decision-making are needed if scenarios are to be relevant for policies with implications in natural resource management. Serious...

Political culture seems to have changed in many Western democracies since Inglehart’s findings about materialism and post-materialism. The European Values Study can trace attitude distributions back to 1981 till 2019. A study series like this one—with identical questions about a wide range of issues—allows for first defining an attitude space commo...

Notwithstanding the huge literature on state studies, both definition and method have always been subject of intense debate. This debate is still open and equally intense despite two millennia of philosophical and methodological attempts to define what the state is, to describe how the state works, and why does it work. As times, geopolitical conte...

Notwithstanding the huge literature on state studies, both definition and method have always been subject of intense debate. This debate is still open and equally intense despite two millennia of philosophical and methodological attempts to define what the state is, to describe how the state works, and why does it work. As times, geopolitical conte...

Manure-based biogas may make an important contribution both to the energy transition and to the reduction in greenhouse gas emissions. Despite these benefits, in Switzerland the use of manure as an energy source is still very limited. The engagement of farmers in biogas production is low and the barriers to their participation are not well known. T...

Agent-based simulation models are often without a direct relation to their target systems in the real world but describe artificial societies, using stylised facts as a basis for modelling. The individuals of these artificial societies are usually endowed with very few capabilities such that their resemblance to human beings is usually poor. Nevert...

Computational models of human societies are usually designed according to protocols like the ODD protocol or supported by ontologies. An alternative to these approaches is basing simulation models on a structuralist reconstruction of the theory underlying the simulation model. This makes it necessary to identify all kinds of entities and all relati...

Mikroanalytische Simulationsmodelle oder kurz Mikrosimulationsmodelle haben eine Geschichte, die bis in die 1950er Jahre zurückreicht. Sie wurden und werden als politisches Beratungsinstrument eingesetzt, indem sie zukünftige gesellschaftliche, insbesondere demographische Entwicklungen abschätzen sowie die Auswirkungen solcher politischer Entscheid...

This is an entry on social simulation in a Handbook

The paper discusses the relation between the “non-statement view” of the structuralist program in philosophy of science and agent-based simulation and the use of this relation for a deeper understanding of the verification and the validation of simulation models. To this end it uses the history of the gender desegregation process in German schools...

The paper shows that in an artificial society lawlike rules emerge “as a result of individual action but without being designed by any individual” agents (Hayek, 1944, p. 288) and discusses earlier literature on the topic. The first example that this paper uses is an artificial society of car drivers moving between their homes and their working pla...

This chapter gives an overview of early attempts at modelling social processes in computer simulations. It discusses the early attempts, its successes and its shortcomings and tries to identify some of them as forerunners of modern simulation approaches.

The paper describes a simulation model of conflict escalation in criminal organizations, investigating conditions of stability and collapse of the organization. As a paradigmatic case, the Sicilian Cosa Nostra provides the background for the formulation of the model assumptions. Cosa Nostra faced two so-called Mafia wars. Outbreak of wars is replic...

The aim of the paper is to discuss the possibility of using complex software agents in a simulation model in order to represent and analyse the dynamics of certain types of criminal systems via Agent Based Modelling (ABM), in particular Extortion Racket Systems (ERSs). It presents a simulation model and the results of a large number of runs to find...

Many simulation models just model stylised facts, and as such they are interesting and often helpful. But simulation models can be seen as an implementation of theory in a computer, and this is why at least an empirical validation should be aimed at. And if a simulation model is to be validated in a concrete empirical setting, it should be initiali...

The paper uses Schelling’s famous segregation model and a number of extensions to show how a reconstruction of the theory behind these models along the lines of the ‘non-statement view’ on empirical science can contribute to a better understanding of these models and a more straightforward implementation. A short introduction to the procedure of re...

Die Soziologie ist nicht nur eine multiparadigmatisch angelegte Wissenschaft, sie hat in ihrer Genese auch zahlreiche methodische Ansätze hervorgebracht. Nicht nur die Unterscheidung zwischen qualitativer und quantitativer Methode ist hierbei entscheidend. Innerhalb des jeweiligen Forschungsparadigmas haben sich in den letzten Jahrzehnten wiederum...

The aim of this chapter is to summarise the problems incurred during the phases of calibrating and validating the extortion racket models used by the GLODERS project. The chapter starts with the discussion of the data availability and summarises shortly the contents of Sect. 4. 3. It continues with a discussion of what parameterisation, calibration...

The aim of this chapter is to document the event-oriented version of the NetLogo model of normative agents in extortion racket systems (ERSs). It presents a simulation model in which agents represent Mafiosi, their victims, the police, the public (mainly in their role as consumers) and a court which—besides extorting and forming Mafia families, den...

A first challenge in characterising and quantifying the nature and dimension of the extortion rackets phenomenon worldwide is that extortion is an umbrella concept grouping a large array of criminal practices. Extortion is often associated with long-standing and well-organised criminal organisations, such as the Italian Mafia and the Japanese Yakuz...

The available survey data sources can only give an incomplete access to the empirical problem under consideration for the reasons discussed in more depth in Sect. 12. 1, but anyway three surveys can be used as sources for finding out which norm orientations prevail in the regions under consideration in GLODERS and which are the propensities and fre...

Protection racketeering groups are powerful, deeply entrenched in multiple societies across the globe, and they harm the societies and economies in which they operate in multiple ways. These reasons make their dynamics important to understand and an objective of both scientific and application-oriented interest. Legal and social norm-based approach...

The presentation describes and discusses a simulation model of a Mafia type extortion racket system and uses it for evaluating intervention strategies.

This article discusses the question of whether significance tests on simulation results are meaningful at all. It is also argued that it is the effect size much more than the existence of the effect is what matters. It is the description of the distribution function of the stochastic process incorporated in the simulation model which is important....

The paper discusses distribution effects of extortion racket systems which are quite frequent in several countries and sometimes are responsible for an unexpectedly high proportion of the regional gross domestic product. The model presented here takes a system perspective, leaving individual decision making processes for further publications. It re...

Many simulation models just model stylised facts, and as such they are interesting and often helpful. But simulation models can be seen as an implementation of theory in a computer, and this is why at least an empirical validation should be aimed at. And if a simulation model is to be validated in a concrete empirical setting, it should be initiali...

Extortion racketeering is an industry not only practiced by mafia, but also in groups such as hells angels. It occurs in a complex setting of criminals, victims, police and society, and its framework is set up by legal norms as well as informal norms of the actor groups involved. The paper presents two agent-based simulation models which differ wit...

J. Gary Polhill's forum paper in this issue was an invitation to try the OWL extension on a model that was written more than a year ago. Download and installation was a matter of a few minutes, extending the old model with a few lines as shown in the paper was not a problem either, visualising the OWL output with different versions of Protégé was a...

In this paper we analyze the interplay of inter-organizational (in terms of cognitive distance between organizations) and intra-organizational (in terms of absorptive capacity of an organization) learning in search for innovation (exploration/exploitation), two important levels which have rarely been studied jointly in a single model. Applying the...

Mikrosimulationsmodelle sind in den Sozialwissenschaften, trotz ihrer relativ langen Geschichte, ein sehr selten eingesetztes Instrument zur Analyse gesellschaftlicher Prozesse. Vordergründig werden sie als politisches Beratungsinstrument eingesetzt, welches zukünftige gesellschaftliche Entwicklungen in Form von Szenarien schätzt und so politische...

Many papers on simulation in the social sciences come up with significance tests in which the authors describe the effect of a parameter on some simulation outcome as significant on some level of significance. This chapter discusses the question whether significance tests on simulation results are meaningful, and it argues that it is the effect siz...

Validation of agents' decision making is one of the central epistemological problems in empirical agent-based model (ABM) simulations. This paper focuses on the need for reliable decision-making models for land change science with direct relevance to modelling human-environmental systems for policy implications and natural resources management. Thi...

The paper uses two formal models of simple processes in artificial worlds—one with and one without an analytical solution—to discuss the role of statistical analysis and significance tests of results from multiple simulation runs. Moreover the paper argues that it is not the sheer existence of an effect of input parameters on simulation results but...

The paper proposes a novel research architecture for social scientists that want to employ simulation methods. The new framework gives an integrated view of a research process that involves simulation modelling. It highlights the importance of the theoretical foundation of a simulation model and shows with the help of the non-statement view and its...

Why Read This Chapter? To understand the historical context of simulation in the social sciences and thus to better comprehend the developments and achievements of the field. Abstract This chapter gives an overview of early attempts at modelling social processes in computer simulations. It discusses the early attempts, their successes and shortcomi...

This chapter replaces the fixed access and decision structures of the original garbage can model with the possibility of forming teams based on considerations of the characteristics of problems and the skills of organizational members. In real organizations, members often solve problems in collaboration, either in parallel or sequentially. In an ex...

decision-making models, agent-based/multi-agent system models and simulation, validation, land-use change, critical multiplism

Agent-based modeling of markets The paper gives an overview of agent-based models of markets as they have been published during the past years. Starting from concept-based models which describe the behaviour of market participants in an abstract manner, recent approaches model real markets in order to find out possible future developments and to ev...

This chapter compares the technique of reconstructing theory under the `non-statement view' with the design and implementation of simulation models. For this purpose it uses several different versions of the famous `garbage can' model, redefines this theoretical attempt in terms of the `non-statement view' and compares it to simulation models of di...

This paper describes three fundamental pitfalls or caveats of empirical modeling of land-use decision making in agent-based models for land-use/cover change. A case study in the villages of Jambi Province (Sumatra), Indonesia, is presented to demonstrate the construction of empirical decision-making models using utility functions while taking into...

German demographic or educational projections are conventionally based on macrosimulation or period microsimulation models. In this paper we introduce a discrete-event microsimulation model, which we have designed to project the graduate rates of the German population. In this model we use survival functions to calculate different fertility rates b...

This paper deals with EMIL-S, a software tool box which was designed during the EMIL project for the simulation of processes during which norms emerged in an agent society. This tool box implements the cognitive architecture of normative agents which was designed during the EMIL project which is also discussed in other papers in this issue. This im...

Context is everywhere in the human social and cognitive spheres but it is often implicit and unnoticed. However, when one is involved in trying to understand and model the social and cognitive realms context becomes an important factor. This paper is ...

Human social systems are the most complex systems that we can conceive of, as interaction among their members is by messages that have to interpreted before they can take any effect – and the interpretation of identical messages sent and received in identical situations can have divergent effects as human actors have long-term memories, which makes...

Social simulation is often described as a multidisciplinary and fast-moving field. This can make it difficult to obtain an overview of the field both for contributing researchers and for outsiders who are interested in social simulation. The Journal for Artificial Societies and Social Simulation (JASSS) completing its tenth year provides a good opp...

The problem of designing a municipal clinic website and selecting a number of its elements ensuring proper, ergonomic, and easily accessed services is discussed. The poor performance of the website infrastructure of state and municipal healthcare institutions necessitated an analysis of web resources used in different countries at different stages...

Our paper describes asexually reproducing agents in a sugarscape-like world who move around and feed on resources. Agents have a number of possible actions: to move, gather food, breed offspring, subordinate and unsubordinate, start and end coordinating, and, last but not least, to rest. Some of the agents may act as coordinators for others. Coordi...

The article discusses the sociological background and the general features of a new simulation toolbox, which was explicitly designed to describe, design and simulate multi-agent systems whose component agents are endowed with the capability to exchange norm invocations and to internalize norms, to develop codes of norms and to change them. This to...

Human social systems are the most complex systems that we can conceive of, as interaction among their members is by messages which have to be interpreted before they can take any effect — and the interpretation of identical messages sent and received in identical situations can have divergent effects as human actors have long-term memories which ma...

This talk argued that the agent-based simulation approach is just the one appropriate to the social sciences (including economics). Although there were many predecessor approaches, which tried to build formal models of social systems, all of them fell short of the peculiar features of the objects of all social sciences: complex systems consisting o...

This paper argues that the agent-based simulation approach is just the one appropriate to the social sciences (includ- ing economics). Although there were many predecessor ap- proaches, which tried to build formal models of social sys- tems, all of them fell short of the peculiar features of the objects of all social sciences: complex systems consi...

Modelling situations in which agents can take offence at other agents' behaviour enables them to invent, learn and evolve social rules in a realistic way. Multiagent systems—collections of computer programs capable of autonomous action—have been used for social simulation for two decades, and especially to generate artificial societies in which fea...

Glossary Definition of the Subject Introduction Social Processes and Social Systems System Dynamics Microanalytical Simulation Multilevel Simulation Multi-Agent Simulation Tools Future Directions Bibliography

This short comment on Epstein's (2008) paper and on the response by Thompson and Derr argues that the symmetry between explanation and prediction cannot satisfactorily be discussed without making clear what prediction means - depending on which connotations the authors have with 'prediction' their arguments can or cannot be accepted.

As social and economic systems are among the most complex systems in our world, the chapter will mainly deal with applications of simulation in general and agent-based simulation in particular in eco- nomics and the social sciences. Thus it will start with a discussion of the predecessors and origins of agent-based simulation mainly, but not only,...

The paper introduces the structuralist concept of theory reconstruction with a trivial model from physics and afterwards applies it to several versions of the garbage can model of organisational behaviour. It shows that simulation and theory reconstruction are to some extent equivalent. The paper also presents a new version of the garbage can model...

The simulation of social behavior in a variety of domains is an increasingly important technological tool. A reference survey of social simulation work, Social Simulation: Technologies, Advances and New Discoveries comprehensively collects the most exciting developments in the field. Drawing research contributions from a vibrant community of expert...

There is strong evidence that computer simulation is increasingly recognized as an important analytical tool in many social sciences disciplines and fields. During the last ten years, a number of new journals, which are devoted to this field, have been founded and others have increased their influence (i.e., JASSS, CMOT, Social Science Computer Rev...

In our paper we present a simulation tool which allows simulation of social processes in a multi-agent system where agents decide according to fuzzy-logic rules. The tool offers a toroidal, but as compared to the famous Sugarscape, continuous world in which, as in Sug-arscape, two plant species (spice and sugar) and arbitrarily many agents of diffe...

This special section includes papers originally presented at a workshop on \'Epistemological Perspectives on Simulation\' in July 2004 at the University of Koblenz, in which some thirty colleagues participated. It had been our impression that there was (and still is) a small, but growing number of researchers who are interested in investigating the...

This paper discusses aspects of validating simulation models designed to describe, explain and predict real-world phenomena. It starts with a short review of argu-ments used in the simsoc mailing list discussion on the-ory, simulation and explanation a few months ago, deals with the use of quantitative and qualitative computational models to make q...

Alle Sozialwissenschaften beschäftigen sich mit komplexen Systemen, in denen große Zahlen von Komponenten einander beeinflussen, und dies — vor allem im Vergleich zu den Naturwissenschaften — in höchst vielfältiger Form. Manche dieser Einflüsse mögen stochastischer Natur sein, jedenfalls können sie leicht als stochastisch modelliert werden; manche...

In our paper, we replicate simulation experiments carried out some 30 years by Jay M. Anderson who then tried to find out which measures should be taken avoid the eutrophication of a lake. In his DYNAMO model, he simulated the development of a lake under cultural eutrophication, i.e. mainly by the discharge of fertilisers from agriculture. He desig...

The use of computer simulations to study social phenomena has grown rapidly during the last few years. Many social scientists from the fields of economics, sociology, psychology and other disciplines now use computer simulations to study a wide range of social phenomena. The availability of powerful personal computers, the development of multidisci...

Das Kapitel geht von der logistischen Gleichung für das Wachstum einzelner (oder mehrerer unverbundener) Populationen und vom Volterra-Lotka-Modell zweier Populationen aus, entwickelt — zunächst auf der Ebene der Populationen — ein Modell für die Interaktionen zwischen mehreren Populationen und untersucht die Fixpunkte des sie beschreibenden Differ...

Microsimulation en sciences sociales. Ci-dessous se trouvent trois articles basés sur des présentations et des discussions qui ont eu lieu au Séminaire de Dagstuhl sur la microsimulation en sciences sociales: "Une défi à l'informatique". Schloβ Dagstuhl. 1-5 mai 1995, et ont été publiés depuis dans K. G. Troitzsch, U. Mueller, G. N. Gilbert et J.E....

In this paper we describe the use of computer simulation in the social sciences and economics. These sciences deal with complex systems in which large numbers of components influence each other in a large variety of ways, and some of these influences are stochastic or can best be modeled as stochastic. After a short overview of the history of simul...