Heuristic learning and the discovery of specialization and exchange

I develop and calibrate an agent-based model of boundedly rational, adaptive agents in a two-good production and exchange economy to replicate human-subject outcomes in the same eight-person experimental economy. To test agents’ ability to capture human behavior, I extend the model and use its output to make predictions about a second experimental environment in which the group of eight agents is slowly constructed by merging smaller groups. This environment improves human-subject performance in the specialization and exchange task, and commensurate improvement emerges for some parameterizations of the agent-based model. This iterative process yields incremental improvement of decision-level theories about economic discovery.     

Ein Index zur numerischen Bestimmung der Niveau-Eigenschaft eines psychologischen Tests

Zusammenfassung Es wird ein Index definiert, der den Grad, in dem ein Intelligenz- oder Leistungstest die Eigenschaften und Bedingungen eines ideal-typischen Niveau-Tests erfüllt, kennzeichnet. Der Index variiert in den Grenzen von 0 bis 1, wobei der Wert 0 einem idealtypischen Schnelligkeitstest (Speed-Test) und der Wert 1 einem idealtypischen Niveau-Test entspricht. Dieser Index kann aufgrund einer einmaligen Testdurchführung bestimmt werden; er ist abh?ngig von der Zeitbegrenzung des Testes und vom Leistungsniveau der untersuchten Stichprobe. Es wird vorgeschlagen, einen Test mitw> > 0,7 als Niveautest, einen solchen mitw<0,3 als Schnelligkeitstest zu bewerten. Die Berechnung vonw wird an Hand bekannter Tests demonstriert und einige Anwendungsbeschr?nkungen er?rtert.

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Summary An index (w) for determining a test as to its degree of being a speed or a power test is proposed varying like a coefficient of correlation from zero to one. This index may be derived from a single testing a posteriori. It is dependent on the given time limit and on the achievement level of the sample tested. From empirical evidence it is suggested to accept a test with an indexw>0,7 as a power test and a test withw<0,3 as a speed test. Numerical examples for calculatingw are given and some restrictions for its application are discussed.

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Herrn Prof. H. Münzner (Berlin) danken die Verfasser für die Durchsicht des Manuskriptes und für seine wertvollen Anregungen.     

The Deterrence Effect of Law Enforcement: An Evaluation of Recent Findings and Some New Evidence

Abstract . Six attempts to measure the deterrence effect of law enforcement on certain criminal activities, as well as one by the author, have produced no clear, unequivocal evidence to support the belief that increased public expenditures on law enforcement have a deterrent effect on such activity. Yet the effect may exist. Further research into the measurement of the variables crime and enforcement and upon the nature of the relationship between them must be carried on before definite conclusions can be reached about the existence of the deterrence effect.     

Modelling the Ecological Comorbidity of Acute Respiratory Infection,Diarrhoea and Stunting among Children Under the Age of 5 Years in Somalia

The aim of this study was to assess spatial co‐occurrence of acute respiratory infections (ARI), diarrhoea and stunting among children of the age between 6 and 59 months in Somalia. Data were obtained from routine biannual nutrition surveys conducted by the Food and Agriculture Organization 2007–2010. A Bayesian hierarchical geostatistical shared component model was fitted to the residual spatial components of the three health conditions. Risk maps of the common spatial effects at 1×1 km resolution were derived. The empirical correlations of the enumeration area proportion were 0.37, 0.63 and 0.66 for ARI and stunting, diarrhoea and stunting and ARI and diarrhoea, respectively. Spatially, the posterior residual effects ranged 0.03–20.98, 0.16–6.37 and 0.08–9.66 for shared component between ARI and stunting, diarrhoea and stunting and ARI and diarrhoea, respectively. The analysis showed clearly that the spatial shared component between ARI, diarrhoea and stunting was higher in the southern part of the country. Interventions aimed at controlling and mitigating the adverse effects of these three childhood health conditions should focus on their common putative risk factors, particularly in the South in Somalia.     

How useful are signals? A micro-structure analysis

We analyze how the market processes a signaling event by studying a sample of self-tender offers, events often viewed as signals of firm value. By examining changes in the degree of informed trading, we find asymmetric information costs fall at announcement, remain low throughout the event, and increase at offer expiration. By one month following expiration, informed trading returns to a level not significantly different from that prior to the offer. Higher risk firms have significantly larger declines in information asymmetry during the offer. Increases in information asymmetry persist one month following expiration for firms with lower pre-offer informed trading. (JEL G14, G32)