Firm–bank credit network,business cycle and macroprudential policy

We present an agent-based model to study firm–bank credit market interactions in different phases of the business cycle. The business cycle is exogenously set, and it can give rise to various scenarios. Compared to other models in this literature strand, we improve the mechanism according to which the dividends are distributed, including the possibility of stock repurchase by firms. In addition, we locate firms and banks over a space and firms may ask credit to many banks, resulting in a complex spatial network. The model reproduces a long list of stylized facts and their dynamic evolution as described by the cross-correlations among model variables. The model allows us to test the effectiveness of rules designed by the current financial regulation, such as the Basel III countercyclical capital buffer. We find that the effectiveness of this rule changes in different business cycle environments and this should be considered by policy makers.

     

协同设计中并发控制策略的研究

文章讨论了各种不同并发控制方法,针对协同交互并发算法中并发度和同步机制不能同时兼顾、并发算法开发复杂的问题,给出了基于并发冲突检测与并发冲突处理相结合的并发控制算法,有效地平衡了并发度和同步机制,提高了协同工作的效率。     

Prospect Theory in the Heterogeneous Agent Model

Using the Heterogeneous Agent Model framework, we incorporate an extension based on Prospect Theory into a popular agent-based asset pricing model. This extension covers the phenomenon of loss aversion manifested in risk aversion and asymmetric treatment of gains and losses. Using Monte Carlo methods, we investigate behavior and statistical properties of the extended model and assess how our extension is manifested in different strategies. We show that, on the one hand, the Prospect Theory extension keeps the essential underlying mechanics of the model intact, but on the other hand it considerably changes the model dynamics. Stability of the model is increased and fundamentalists may be able to survive in the market more easily. When only the fundamentalists are loss-averse, other strategies profit more.

     

Collaboration in Multi-Partner R&D Projects: The Impact of Partnering Scale and Scope

How can firms design collaboration structures for effective performance in R&D projects that involve multiple partners? To address this question, we examine the theoretical underpinnings of collaboration structures in multi-partner R&D projects—i.e., the scale and the scope of partnering efforts. Partnering scale captures the extent of resource interdependencies between a firm and its partners; partnering scope captures both the breadth and depth of the interdependencies between a firm and its partners. Using primary data from 147 multi-partner R&D projects, we develop and test hypotheses that examine the impact of partnering scale and scope decisions on partnering performance. Results indicate that partnering scale has a curvilinear relationship with partnering performance. That is, intermediate levels of partnering scale are associated with higher partnering performance, compared to low or high levels of partnering scale. However, we also find that the nature of this relationship is moderated by the sub-dimensions of partnering scope. Specifically, increase in partnering breadth appears to magnify the negative effect of partnering scale on performance. In contrast, increase in partnering depth appears to overcome this negative effect, allowing firms to operate at higher levels of partnering scale. Taken together, these results highlight the importance of adopting a comprehensive approach to designing collaboration structures for multi-partner R&D projects.     

A Note on Intraday Event Studies

Abstract

We investigate the specification and power of intraday event study test statistics. Mean, market, and matched firm models generate well-specified return results for a range of intervals up to 60?min around the event. These models detect return shocks equivalent to one spread in one-minute interval data and three spreads in longer intervals. Researchers using intraday return event studies can, therefore, be confident in their robustness. Some volume event study approaches have reasonable power but they are not generally well specified, while a matched-firm approach gives the best combination of specification and power for spread event studies.     

Network position and health care worker infections

We use a newly collected data set coupled with an agent-based model to study the spread of infectious disease in hospitals. We estimate the average and marginal infections created by various worker groups in a hospital as a function of their network position in order to identify groups most crucial in a hospital-based epidemic. Surprisingly, we find that many groups with primary patient care responsibilities play a small role in spreading an infectious disease within our hospital data set. We also demonstrate that the effect of different network positions can be as important as the effect of different transmission rates for some categories of workers.     

Testing the convergence hypothesis: a longitudinal and cross-sectional analysis of the world trade web through social network and statistical analyses

Different theoretical perspectives support opposite views on convergence: although the dominant view is that convergence is the inevitable outcome of globalization, divergentists (that is, world-system economists and, potentially, also evolutionary geographic ones) argue that convergence forces could be annihilated by the need to keep power relationships within the international division of labor. Even when limiting the convergence issue to international trade, the debate has so far been inconclusive, because various studies have dealt with different and/or short time series or selected too small and different sets of countries. Moreover, none of these studies have analyzed trade patterns and have instead been limited to the aggregate value. Here, through a social network analysis, we examine the world trade patterns from 1980 to 2016 (1980–1992, 1993–2007 and 2008–2016) of at least 164 countries, which have been divided into import and export patterns and into four groups of countries: from core countries to far periphery ones. We test the convergence hypothesis in two directions: the level and trend of convergence, and its possible determination by means of structural or economic globalization, measured in terms of exchanges density and economic values, respectively. We have found that the convergence hypothesis only seems to be confirmed when considering the pure structural aspect and core countries. Conversely, economic convergence—which also includes the structural dimension—has been found to be high for core countries and to increase over time. Moreover, our analysis shows that economic globalization influences convergence, albeit in a strongly negative way. Therefore, our findings seem to support divergentists and the convergence hypothesis should be rejected.

     

Crack spread option pricing with copulas

A copula-based approach for pricing crack spread options is described. Crack spread options are currently priced assuming joint normal distributions of returns and linear dependence. Statistical evidence indicates that these assumptions are at odds with the empirical data. Furthermore, the unique features of energy commodities, such as mean reversion and seasonality, are ignored in standard models. We develop two copula-based crack spread option models using a simulation approach that address these gaps. Our results indicate that the Gumbel copula and standard models (binomial, and Kirk and Aron (1995)) mis-price a crack spread option and that the Clayton model is more appropriate. We contribute to the energy derivatives literature by illustrating the application of copula models to the pricing of a heating oil–crude oil “crack” spread option.     

Transaction taxes, greed and risk aversion in an agent-based financial market model

Recent agent-based financial market models came to the result that taxing financial transactions does not per se increase financial stability and that the response of volatility and misalignments to rising tax rates seem to be u-shaped. Moreover, greed and the risk appetite of traders are often blamed for financial instability and there is no evidence how greed and risk aversion affect the effectiveness of regulations in financial markets. We aim to add to this gap in the literature by analyzing how the effectiveness of transaction taxes depend on different behavioral patterns within an agent-based framework. Our simulations indicate that a tax rate of 0.1% demarcates the stabilizing tax regime from the destabilizing one. We figure out that transaction taxes are less effective, either when chartists trade more aggressively, fundamentalists trade less aggressively, agents switch more frequently between trading strategies or only have short memory in their fitness measures. Lower risk aversion of agents, however, makes higher tax rates more effective as indicated by a flatter volatility response curve. We conclude that additional regulations should concentrate on the traders’ responsibilities for their risk-exposure.     

Concurrent and disconnected change programmes: strategies in support of servitization and the implementation of business partnering

For many leading engineering companies, the integration of services into product offerings is seen to comprise an important shift in the underlying business model. This movement has been termed the ‘servitization of business’. Within this debate, however, scant attention has been given to the human resource (HR) implications of servitization. An exploratory case study illustrates the HR challenges associated with servitization and the way in which these interact with a concurrent change programme concerned with the implementation of ‘business partnering’. The findings highlight the emergent complexities resulting from these two change programmes being rolled out simultaneously. Although contested across different divisions, the shift to servitization continuously disrupts the implementation of business partnering with little alignment between the two espoused initiatives. Furthermore, the rate of strategic change within the company in response to changing markets continuously acts to erode the coherence of the acclaimed move to business partnering. In consequence, the HR policies and practices struggle to maintain contact with the company's strategic direction.     

Expectation formation of older married couples and the rational expectations hypothesis

This paper tests the Rational Expectations (RE) hypothesis regarding retirement expectations of older married American couples, controlling for sample selection and reporting biases. In prior research we found that individual retirement expectation formation was consistent with the Rational Expectation hypothesis, but in that work spousal considerations were not analyzed. In this research we take advantage of panel data on expectations to test the RE hypothesis among married individuals as well as joint expectations among couples. We find that regardless of whether we assume that married individuals form their own expectations taking spouse's information as exogenous, or the reports of the couple are the result of a joint expectation formation process, their expectations are consistent with the RE hypothesis. Our results support a wide variety of models in economics that assume rational behavior of married couples.     

Agent-based modeling of the word-of-mouth effect on promoting brand-name agricultural products

Developing brand agricultural products (BAPs) has become a strategic choice for consumption upgrading and agricultural modernization in China. As a powerful marketing method, word-of-mouth (WOM) is rarely applied to BAPs. Based on the particularity of the agricultural environment and products in China, this paper focuses on the WOM behavior of consumers regarding BAPs. An agent-based simulation model was designed, including attitude and motivation functions. The former determines consumers’ attitudes toward BAPs, whereas the latter determines whether consumers will spread information by WOM. The model was validated, and some parameters were measured through a survey of Beijing consumers. Then, experiments were conducted to simulate the evolution process of consumers’ attitudes and willingness to engage in WOM and the influence of consumer heterogeneity on WOM spreading. Exploratory findings mainly show that (1) only when the strength of WOM marketing reaches a certain degree can it affect consumer attitudes toward BAPs, (2) in the early stage of WOM spreading, the greater the strength of economic stimulation to consumers, the greater the rate of WOM communication, and (3) the higher the education level of the target group of WOM marketing, the higher the efficiency of WOM communication.

     

Simple agent-based dynamical system models for efficient financial markets: Theory and examples

We propose an agent-based framework, based on simple piecewise linear time-invariant continuous-time dynamical systems models, as a means for describing efficient financial markets. We show by examples that many of the common agent-specific trading strategies occurring in the academic literature, including chartists and fundamentalists of various kinds, can be described in the proposed framework. We present definitions for weak and strong market efficiency and provide necessary and sufficient conditions for them to hold. We present minimal examples of strongly and weakly efficient markets to show that these concepts are natural and easy to satisfy in agent-based models, and that the models can reproduce both statistical and behavioral stylized facts of real markets. We provide examples to demonstrate that the framework can be extended for agents with delays in information processing, as well as for agents with time-varying strategies and for nonlinear market impact functions. We also provide a counterexample to show that the proposed market efficiency concepts may require modification in generalizations for nonlinear trading strategies.     

Diffusion and spatial equilibrium of a social norm: voting participation in the United States, 1920–2008

Social conformity can spread social norms and behaviors through a society. This research examines such a process geographically and over time for voting, which is strongly influenced by the norm that citizens should vote. A mathematical model for the spread of voting participation under the influence of social conformity is developed based on the diffusion equation, and predictions are tested with spatial analysis of state-level voter turnout in American presidential elections from 1920 to 2008. Results show that voter turnout has converged to a stable equilibrium in its geographical distribution across the states—but it is an equilibrium that results in persistent differences at the state level. Results are compared to individual-level and agent-based models. The model may be applied to other types of social diffusion that depend on specific geographical location.     

Validating an agent-based model of the Zipf׳s Law: A discrete Markov-chain approach

This study discusses the validation of an agent-based model of emergent city systems with heterogeneous agents. To this end, it proposes a simplified version of the original agent-based model and subjects it to mathematical analysis. The proposed model is transformed into an analytically tractable discrete Markov model, and its city size distribution is examined. Its discrete nature allows the Markov model to be used to validate the algorithms of computational agent-based models. We show that the Markov chains lead to a power-law distribution when the ranges of migration options are randomly distributed across the agent population. We also identify sufficient conditions under which the Markov chains produce the Zipf׳s Law, which has never been done within a discrete framework. The conditions under which our simplified model yields the Zipf׳s Law are in agreement with, and thus validate, the configurations of the original heterogeneous agent-based model.     

A comparison of different trading protocols in an agent-based market

We compare price dynamics of different market protocols (batch auction, continuous double auction and dealership) in an agent-based artificial exchange. In order to distinguish the effects of market architectures alone, we use a controlled environment where allocative and informational issues are neglected and agents do not optimize or learn. Hence, we rule out the possibility that the behavior of traders drives the price dynamics. Aiming to compare price stability and execution quality in broad sense, we analyze standard deviation, excess kurtosis, tail exponent of returns, volume, perceived gain by traders and bid-ask spread. Overall, a dealership market appears to be the best candidate, generating low volume and volatility, virtually no excess kurtosis and high perceived gain.     

Innovation,finance, and economic growth: an agent-based approach

This paper extends the endogenous growth agent-based model in Fagiolo and Dosi (Struct Change Econ Dyn 14(3):237–273, 2003) to study the finance–growth nexus. We explore industries where firms produce a homogeneous good using existing technologies, perform R&D activities to introduce new techniques, and imitate the most productive practices. Unlike the original model, we assume that both exploration and imitation require resources provided by banks, which pool agent savings and finance new projects via loans. We find that banking activity has a positive impact on growth. However, excessive financialization can hamper growth. Indeed, we find a significant and robust inverted U-shaped relation between financial depth and growth. Overall, our results stress the fundamental (and still poorly understood) role played by innovation in the finance–growth nexus.

     

Recent advances in financial networks and agent-based model validation

We introduce the papers appearing in the special issue of this journal associated with the WEHIA 2015. The papers in issue deal with two growing fields in the in the literature inspired by the complexity-based approach to economic analysis. The first group of contributions develops network models of financial systems and show how these models can shed light on relevant issues that emerged in the aftermath of the last financial crisis. The second group of contributions deals with the issue of validation of agent-based model. Agent-based models have proven extremely useful to account for key features economic dynamics that are usually neglected by more standard models. At the same time, agent-based models have been criticized for the lack of an adequate validation against empirical data. The works in this issue propose useful techniques to validate agent-based models, thus contributing to the wider diffusion of these models in the economic discipline.     

On the plausibility of sunspot equilibria

This study examines the plausibility of the emergence of sunspot equilibria in an agent-based artificial stock market. Using the agent-based model, we make the sunspots explicit so that we can test, e.g., by means of the Granger causality test, whether purely extrinsic uncertainty can influence price dynamics. In addition, through agent-based simulation, the coordination process, which is mainly driven by genetic programming, becomes observable, which enables us to analyze what agents perceive and whether they believe in sunspots. By manipulating different control variables, three series of experiments are conducted. Generally speaking, the chances of observing “sunspot equilibria” in this agent-based artificial stock market are small. However, the sunspot believers can never be driven out of the market. Nevertheless, they are always outnumbered by fundamental believers, which is evidence that the market as collective behavior is rational. We also find that lengthening the time horizon will make it difficult for sunspot believers to survive.     

Some simple mathematical models for adoption processes: The case of the comprehensive school reform in Norway

This article reviews simple mathematical models which have been or may be used for adoptation processes. Each model's role in the explanation process is analyzed.

The case of the spread of the comprehensive school reform in Norway is used to ilustrate an adoption process. The logistic, or chain-reaction model, and a normal model for independent adoption are emphasized. The fit of the curves for the provinces and the whole country favors the logistic model. Evidence of a “neighborhood effect” at the micro-level also points to a communication process.