Integrated bio-economic models as tools to support land-use decision making: a review of potential and limitations

Bio-economic modelling has become a useful tool for anticipating the outcomes of policies and technologies before their implementation. Advances in mathematical programming have made it possible to build more comprehensive models. In an overview of recent studies about bio-economic models applied to land-use problems in agriculture and forestry, we evaluated how aspects such as uncertainty, multiple objective functions, system dynamics and time have been incorporated into models. We found that single objective models were more frequently applied at the farm level, while multiple objective modelling has been applied to meet concerns at the landscape level. Among the objectives, social aspects are seldom represented in all models, when being compared to economic and environmental aspects. The integration of uncertainty is occasionally a topic, while stochastic approaches are more frequently applied than non-stochastic robust methods. Most multiple-objective models do not integrate uncertainty or sequential decision making. Static approaches continue to be more recurrent than truly dynamic models. Even though integrating multiple aspects may enhance our understanding of a system; it involves a tradeoff between complexity and robustness of the results obtained. Land-use models have to address this balance between complexity and robustness in order to evolve towards robust multiple-objective spatial optimization as a prerequisite to achieve sustainability goals.     

Ownership of Cross–Listed Equities: An Investigation of Turnover, Diversification, and Risk

Using data for a sample of Malaysian stocks that are traded in both Malaysia and Singapore, we show that the turnover rate (trading volume relative to shares held) is significantly higher in the foreign market than in the domestic market. We also find that ownership of cross–listed shares by foreign investors is not motivated by diversification benefits. Instead, we find that the proportion of a firm's shares held in Singapore is directly related to the firm's level of systematic risk.     

Evidence on agglomeration economies,diseconomies, and growth

Conventional urban economic analysis suggests that a local economy's size is closely related to a number of features, including levels of human capital and the availability of specialized inputs, which are likely to influence positively the rate at which it accumulates further economic activity. At the same time, urban theory also suggests that once cities reach a certain level of size, these agglomeration benefits begin to peter out, while diseconomies rise rapidly. Consequently, we should see an ‘inverted U‐shaped’ pattern of growth with respect to economic size—rates of growth first rise, then fall as size increases. This paper shows that, while such a pattern is largely absent from recent data on growth in metropolitan area population and employment, it emerges strikingly in county‐level data. Copyright © 2002 John Wiley & Sons, Ltd.     

Migration Policy in a Small Open Economy with a Dual Labor Market

The paper uses a two–sector efficiency–wage model to analyze the consequences of immigration for a small open economy with a dual labor market. Immigrants are characterized by an (exogenous) return probability. Legal regulations impose preferential hiring of natives or "old" immigrants. As a result, there is sectoral segregation between natives and immigrants, leading to discrimination of the type equal pay for equal work,but unequal "work." In the short run (with sector–specific capital), immigration has a positive first–order impact on natives' welfare if migration policy favors segregation through high return rates or restrictive hiring practices ("guest–worker system"). In the long run, its effect is only determined by factor intensities (2 ¥ 2 model). Finally, the improved integration of migrants yields efficiency gains and improves aggregate welfare of all residents.     

DURATION MOMENTS AND YIELD CURVE MOVEMENTS

In this paper we will analyze the relationship between the value and duration moments of a cash flow and movements in the yield curve. We will show that for changes in the yield curve which can be related to tⁿ , the 1st order changes in the net present value of a cash flow are linearly dependent on the n + lth duration moments, and that the 2nd order changes are dependent on the sum of duration moments of order 2 n + 1 and 2 n + 2. We will use this relationship to tilt tracking portfolios so as to protect them against specific changes in the yield curve.