The Narrow and Broad Approaches to Evolutionary Modeling in Economics

Some models in evolutionary economics rely on direct analogies to genetic evolution, assuming a population of firms with routines, technologies, and strategies on which forces of diversity generation and selection act. This narrow conception can build upon previous findings from evolutionary biology. Broader concepts of evolution allow many or just one adaptive entity, instead of necessarily requiring a population. Thus, an institution or a society can also be understood as an evolutionary entity. Both the narrow and broad approaches have been extensively used in the literature, albeit in different literature traditions. I provide an overview of the conception and development of both approaches to evolutionary modeling, and argue that a generalization is needed to realize the full potential of evolutionary modeling.     

COMPETITIVENESS AND STABILITY OF COLLUSIVE BEHAVIOR

We investigate the relationship between the degree of competition and the stability of collusive behaviour, by introducing the element of relative performance in the objective functions of the firms. We show that an increase in the degree of competition destabilizes the collusion. This relation differs starkly in the standard symmetric Cournot and Bertrand duopoly models, with the former being more unstable than the latter.     

对某古滑坡稳定性分析的探讨

古滑坡是一种不良地质现象,易诱发为地质灾害,对人类生命财产安全造成危害。本文以某古滑坡工程勘察实例为基础,对其成因及稳定性进行了分析评价,最后笔者得出了该古滑坡处于稳定状态,对工程影响不大,从而节约了工程投资。     

Temporal stability of preferences and willingness to pay for natural areas in choice experiments: A test–retest

The main objective of this paper is to test the temporal stability of stated preferences and willingness to pay (WTP) values from a Choice Experiment (CE) in a test–retest. The same group of participants was asked the same choice tasks in an internet-based CE, conducted twice with a time interval of one year without interviewer interference. We examine choice consistency at individual choice task level and transferability of the underlying indirect utility function and associated WTP values. The results show that choices are consistent in 57 percent of the choice occasions. Comparison of the choice models over time shows that the estimated preference and scale parameters are significantly different, suggesting that choice behaviour changed between the two surveys. Differences between marginal WTP estimates for individual choice attributes are statistically significant only at the 10 percent level. However, we show that this can result in significantly different WTP values for policy scenarios. The instability of estimated mean WTP values for different policy scenarios asks for caution when including WTP values in cost-benefit analysis.     

The Output Effect of a Transition to Price Stability When Velocity Is Time Varying

This paper explores the effect of time‐varying velocity on output responses to policies for reducing/stopping inflation. We study a dynamic general equilibrium model with sticky prices in which we introduce time‐varying velocity. Specifically, we endogenize time‐varying velocity into the model developed by Ireland (1997) for analyzing optimal disinflation. The nonlinear solution method reveals that, depending on velocity, the “disinflationary boom” found by Ball (1994) may disappear even under perfect credibility and that early output losses may be much larger than previously thought. Indeed, we find that a gradual disinflation from a low inflation may even be undesirable.     

Measuring market distortion: international comparisons,policy and competitiveness

This paper develops a framework to simultaneously estimate production possibility frontiers and measure distortions in factor and product markets. The econometric results, based on a panel of 61 countries over the period 1970 through 1985, reveal very little distortion in factor markets but considerable distortion in product markets. In addition, the distortions tend to vary with the cyclical behaviour of economic activity. Further, the results suggest that in order to improve efficiency, commercial policy should aim at reducing product-market distortions rather than factor-market ones.     

Stability of international stock market relationships across month of the year and different holding intervals

Potential benefits from international diversification depend upon the stability in stock market relationships. Using monthly data of 11 international stock markets, this paper examines the stability in stock market relationships across month of the year and across different holding intervals. Empirical results show that the correlation structure is more stable than the covariance structure. While empirical evidence supports the hypothesis that the correlation structure is very stable across different holding intervals, the empirical support for the stability in correlation structure across month of the year is much weaker.     

Saltatory Ontogeny and the Life-History Model: Neglected Processes and Patterns of Evolution

A single cell – an egg – cannot be in the same stabilized state as a differentiated multicellular embryo or reproducing adult. The entire ontogeny must, therefore, consist of a sequence of stabilized states. Ontogeny of a phenotype cannot progress gradually but is a saltatory homeorhetic system, proceeding via natural thresholds from one self organized state to the next, hierarchically ever more complex and specialized. The natural boundaries of ontogeny – the far-from-stabilized thresholds – represent also states when changes can be easiest inserted or induced, and especially in the early ontogeny, from the intervals where evolution (change) can occur. As a result, ontogeny can also be divided into distinct life-history intervals called periods, be it embryo, larva (infant, pup), juvenile, adult and senescence, each divided in turn into phases, and each of these into natural steps. It is left to the imagination of scholars in social sciences to find parallels of saltation in economics and history.     

浅析我国当前通货膨胀的成因及治理对策建议

稳定物价已成为政府宏观调控的重中之重。为避免由于种种原因形成的通货膨胀给我国经济发展带来较大的负面影响,我们必须采取相关措施,要持续的将总量政策和结构政策相很好的组合起来,进行短期应急计划和措施与建立能长期保证制度正常运行并发挥预期功能的制度体系相结合,综合的采取各种各样的政策组合,比较有指向性地使用各种各样的措施在一定程度上减少对造成物价上涨的各种不利因素,抑制通货膨胀蔓延,使我国经济稳定的发展。     

岩土边坡稳定性的遗传算法分析

非线性优化方法主要缺陷在于当边坡土层为非均质复杂条件时,无法保证搜索到安全系数的全局最小解,而只能搜索到局部极小解。基于遗传算法,建立了搜索岩土边坡稳定性分析最小安全系数和滑移面中心坐标与半径的数值方法。问题的可行解在变量搜索区间内搜索,包括滑弧的圆心坐标和半径。数值模拟结果表明,遗传算法搜索到的边坡稳定最小安全系数与理论解是一致的。