Abstract
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, denouncing or satisfying Mafia requests, observing, arresting and convicting criminals, compensating victims from confiscated Mafia assets—send each other norm invocation messages to mutually modify their action propensities. Each agent of each type has a repertoire of norms whose salience it calculates from its memory before deciding to take action; besides agents also calculate the utility of the actions available in the current situation. The current version of the model is event oriented such that each simulation run tells a story of the rise and possible fall of a Mafia regime in a virtual region. The results of a large number of runs are analysed to find out under which parameter constellations governing the normative behaviour of the software agents the model replicates the macro observations in a number of provinces in Southern Italy which are derived from a database of more than 600 actual cases in Sicily and Calabria extracted from police and judicial documents generated during the prosecution of these cases. Thus it is possible to show that certain parameterisations of the model generate extortion databases similar to the empirical database although the richness of information generated by the model is much greater than what can be documented empirically. Finally the simulation model is applied to analysing strategies and their effect on the behaviour of the agents and the system as a whole.
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Notes
- 1.
The model can be downloaded from http://ccl.northwestern.edu/netlogo/models/community/EONOERS.
- 2.
The standard duration of a run is 2 years, which—for 100 shops, 50 extorters, 10 police and 800 customers, some 2000 extortion attempts and 37,000 exchanged invocation messages—takes a standard PC with eight processors about 2 min on an average in batch mode (a single run takes 20–30 min). Three times as many agents of each type with about 5000 extortion attempts and about 100,000 messages exchanged means about 30 min per run. The delays mentioned in Table 8.2 are not calibrated against any empirical data as even the Sicily and Calabria database (see Chap. 6) does not contain sufficient details for such a calibration . The simulated time units can only have a rough correspondence to real-time units.
- 3.
Runs with different numbers of agents per type—e.g. three times as many as mentioned in footnote 16—generate results which are very similar to the ones reported here, but consume disproportionate computing time.
- 4.
That the province of Trapani is different from the other provinces was already clear from the findings in Chap. 9.
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Troitzsch, K.G. (2016). Extortion Rackets: An Event-Oriented Model of Interventions. In: Elsenbroich, C., Anzola, D., Gilbert, N. (eds) Social Dimensions of Organised Crime. Computational Social Sciences. Springer, Cham. https://doi.org/10.1007/978-3-319-45169-5_8
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