Simulating soil fertility and poverty dynamics in Uganda: A bio-economic multi-agent systems approach

Declining soil fertility and increasing rural poverty are major problems facing sub-Saharan agriculture. Bio-economic modeling has been used to analyze the complex interaction between ecological sustainability and rural poverty as well as to explore policy options promoting sustainable development. This paper shows that these models can be further advanced by adopting an agent-based modeling approach. This gives a more realistic representation of diversity in socioeconomic and biophysical terms, allows local interaction between households, and can yield an ex-ante assessment of the distributional consequences of policy intervention. This paper describes the modeling approach and illustrates it with an empirical application to two village communities in the Lake Victoria Crescent of Uganda. It is shown how the model system can be calibrated with and validated against empirical data. The model is used to analyze the potential effect of short-term credit, mineral fertilizer, and improved maize seed on poverty and sustainability. Simulation results suggest substantial reductions in poverty although the incidence of poverty would remain high and these innovations alone would have little effect on the long-term ecological sustainability of the system.     

Competition,variety and technological evolution: A replicator dynamics model

In this paper a model of technological evolution based on replicator dynamics is developed. Such a model is based on a twin characteristics representation of product technology and on a population approach. The model can give a general representation of technological evolution, but this paper concentrates on the relationship between variety and competition. Variety is considered to be a very important variable influencing economic development. By means of the characteristics and population approach adopted in this paper it is possible to distinguish between inter-and intra-technology competition. In this paper it is demonstrated that the variety of the system can only increase if intra-technology competition is more intense than inter-technology competition. Intuitively this implies that new technologies will only be able to emerge if incumbent technologies experience the competition coming from the new ones to be weaker than their own internal competition.     

Modelling demand and supply influences on utilization: A flow demand model to predict hospital utilization at the small area level

This study outlines a model to predict hospital utilization at the small area level within a National Health Service (NHS) institutional context. The proposed approach departs from alternative analyses based on utilization flows of hospital care between a local population and a hospital. A flow demand model is outlined that relates flow demand to utilization flows; models the interaction between hospital supply and utilization of alternative hospitals; captures the process of demand for hospital care, with special attention given to the role of other health care sectors, to the organizational and institutional context of the hospital system and to geographic variations. The flow approach partly overcomes the problem of dealing with simultaneity of determination between supply and demand. A two-part econometric model suitable to estimate the flow demand model for prediction purposes is tested and applied to the Portuguese health care system. The results show the model to be robust and to provide key information for defining future hospital policies at the central level.     

Skilled and unskilled wage dynamics in Italy in the 1990s: changes in individual characteristics,institutions, trade and technology

In this paper, we use individual micro data on workers combined with industry and regional data to study the wage dynamics of skilled and unskilled workers in Italy in the 1991–1998 period. In contrast to previous empirical studies, our data make it possible to analyse, within a single framework, the role of many of the factors indicated in the literature as possible determinants of skilled and unskilled wage dynamics: changes in the individual characteristics of workers, changes in labour market institutions, increasing international integration, and skill‐biased technological progress. Our results show that international integration, both in terms of trade in goods and in terms of international labour mobility, plays a role in determining the wage dynamics of skilled (white‐collar) and unskilled (blue‐collar) workers. Moreover, in line with labour economics research, our findings show that the individual characteristics of workers and the institutional variables are more relevant in explaining skilled and unskilled wage dynamics than wage differentials.     

Nonlinear dynamics in arbitrage of the S&P 500 index and futures: A threshold error-correction model

Using a three-regime threshold error-correction model, we investigate the nonlinear dynamics of the S&P 500 index and futures. First, using the SupLM statistic, we report estimates of two thresholds for the three-regime model to explain the nonlinear dynamics in arbitrage of the S&P 500 index and futures. This provides empirical evidence of the no-arbitrage band predicted by the cost-of-carry model. Second, using quasi-maximum likelihood estimation, we demonstrate that those indexes that are located outside the no-arbitrage band are a nonlinear stationary process of mean-reversion to the no-arbitrage band. However, index and futures that are located within the no-arbitrage band are non-stationary. Third, we confirm an earlier finding that futures price leads the nonlinear mean-reverting behavior of the index but not vice versa. Impulse response function analysis and forecasting performance of three-regime error-correction model reinforce our findings and our estimation results are robust with different specifications of pricing error terms and endogenous variables.     

Learning during audit tasks in the field: A model, methodology, and experiment

Learning during performance of auditing tasks in the field is modeled as a change in the state of an auditor's knowledge base that results from experience during performance of a task. Several hypotheses are proposed and, along with data obtained by means of behavior observation and concurrent verbal protocols, used to interpret the problem-solving behaviors of four first-year auditors who performed an unfamiliar but audit-related task in simulated auditing environments. Significant findings of learning during performance of the experimental task are reported. While the data show that the auditor-subjects continuously encountered new learning situations throughout the task, they are inconclusive regarding learning through improved knowledge content. On the other hand, significant evidence is found that the learning that did occur was manifest by a greater availability of the auditor-subjects' knowledge. The implications of these findings in terms of the nature of audit tasks and the development of more expert-like task behavior are discussed.     

Formal targets, central bank independence and inflation dynamics in the UK: A Markov-Switching approach

We examine inflation and uncertainty in the UK with a version of the Markov Switching model, which allows for changes in the variance as well as in the mean and persistence of a series. We find that the UK’s attempts at exchange rate pegs in the form of shadowing the deutschmark and entering the ERM were ineffective, and in the latter case counterproductive in lowering inflation uncertainty. The 1981 budget, however, greatly lowered uncertainty, and the adoption of a formal inflation target also had a palpable, negative impact on inflation uncertainty. As a suggestive exercise, we examine inflation uncertainty in the US, and find that, over 2005–2008, in the absence of an inflation target, uncertainty rose in the US, while uncertainty remained low in the UK over this period of rising commodity prices and financial turmoil.     

Employment shifts, economic reform and the changes in public/private sector wages in Mexico: 1987–1997

Over the last decade, the public sector in Mexico experienced substantial fiscal reform, divestiture of public enterprises, and the elimination of many regulations affecting pay and employment. This study analyzes the changes in the public/private sector differences in wages during the 1987–1997 period. The results from analyzing microdata from the Encuesta Nacional de Empleo Urbano show that relative public sector wages increased from 1987 to 1997. Most of the relative wage increase in the public sector can be explained by increases in the price of skills and by changes in sorting across sectors. The results have important public policy implications since they suggest that public sector workers earn more and their wages have grown faster than those of their private sector counterparts. As such, policies contemplating public sector reform should take into account the effect of these measures on the inter-sectoral income distribution and the overall economic growth. First version received: April 2000/Final version received: December 2000     

A look at Subjectivism,Intelligibility and Economic Understanding: Essays in honor of Ludwig M. Lachmann on his Eightieth Birthday

Conclusion Due to my focusing the detailed analysis on by far the best chapters in this Festschrift, the reader may be left with a better impression of the book than it deserves. In point of fact, this volume is replete with errors and is most disappointing for a book touted as the most modern, up-to-date version of Austrianism and as a challenge to the economics of Mises. Indeed, the majority of its chapters simply ignore the basic tenets of this school of thought, and several of those that do not ignore praxeology misconstrue it.But it is important that an overall assessment of the work of the followers of Professor Lachmann not be lost sight of amid the welter of minutiae about their specific errors. And, unfortunately it is not just that they are wrong about equilibrium, methodology, hermeneutics, time preference, and so on; even worse, if possible, is the fact that there has been a virtual cessation of focus on real economic problems such as money and banking, business cycles, utility and welfare economics, and monopoly theory. Virtually all that is heard from this quarter is an endless repetition that the market is a process, that equilibrium is a red herring or worse, that no one can ever know anything, and that all is subject to interpretation.It is possible to construct a continuum in this regard. On the one extreme would be the mainstream empiricists, who believe that their regression equations can test economic axioms. This might well be called an overreliance on economic research. On the other extreme would be the followers of Lachmann, who have all but eschewed economic research; the impossibility of knowing the future, the divergence of expectations, radical subjectivism, it would appear, make this an extremely dubious path for them to follow. And as moderates on the continuum are the Misesians, who maintain that history can illustrate but not test theory, and who are nevertheless vitally interested in doing just this type of work.The author wishes to express appreciation for comments and criticisms of an earlier draft to Jeffry Tucker, David Gordon, Murray Rothbard, Michael Edelstein, and two anonymous referees. They, of course, are not responsible for any errors that remain.     

Measurement of Dematerialization/Materialization: A Case Analysis of Energy Saving and Decarbonization in OECD Countries, 1960–95

This article establishes a conceptual framework for dematerialization and materialization, and develops a complete decomposition model for measuring them. Based on our conceptual framework and method, dematerialization in the energy use of the OECD from 1960 to 1995 has been analyzed. During this period, the increase in energy demand was 3597.95 Mtoe. However, the improvement of energy efficiency decreased energy demand by 827.20 Mtoe, and structural shifts decreased energy demand by 139.04 Mtoe. Thus, real energy demand only increased by 2631.71 Mtoe, and the energy saved was 966.24 Mtoe and the energy saving rate was 17.98% for this period. The energy saving rate was about 0.56% per year. In the same period, the increase of CO₂ emissions was 9672.95 Mton. The fuel switching, the improvement of energy efficiency, and structural shifts decreased CO₂ emissions by 1899.67, 2150.31, and 379.07 Mton, respectively. Real CO₂ emissions only increased by 5243.93 Mton, the decarbon was 4429.02 Mton and the decarbonization rate for the period was 29.57%. The decarbon rate was about 0.997% per year. These results show that significant dematerialization has been achieved in the OECD during this period.