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- 2007 (24) (entfernen)
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Agro-biodiversity can provide natural insurance to risk averse farmers. We employ a conceptual ecological-economic model to analyze the choice of agrobiodiversity by risk averse farmers who have access to financial insurance. We study the implications for individually and socially optimal agro-ecosystem management and policy design when on-farm agro-biodiversity, through ecosystem processes at higher hierarchical levels, generates a positive externality on other farmers. We show that for the individual farmer natural insurance from agro-biodiversty and financial insurance are substitutes. While an improved access to financial insurance leads to lower agro-biodiversity, the e_ects on the market failure problem (due to the external benefits of on-farm agro-biodiversity) and on welfare are determined by properties of the agro-ecosystem and agro-biodiversity’s external benefits. We derive a specific condition on agro-ecosystem functioning under which, if financial insurance becomes more accessible, welfare in the absence of regulation increases or decreases.
Credit Constraints, Idiosyncratic Risks, and Wealth Distribution in a Heterogeneous Agent Model
(2007)
This paper examines the effects of credit market imperfections and idiosyncratic risks on occupational choice, capital accumulation, as well as on the income and wealth distribution in a two sector heterogeneous agent general equilibrium model. Workers and firm owners are subject to idiosyncratic shocks. Entrepreneurship is the riskier occupation. Compared to an economy with perfect capital markets, we find for the case of serially correlated shocks that more individuals choose the entrepreneurial profession in the presence of credit constraints, and that the fluctuation between occupations increases too. Workers and entrepreneurs with high individual productivity tend to remain in their present occupation, whereas low productivity individuals are more likely to switch between professions. Interestingly, these results reverse if we assume iid shocks, thus indicating that the nature of the underlying shocks plays an important role for the general equilibrium effects. In general, the likelihood of entrepreneurship increases with individual wealth.
The paper presents first results and ideas from an ongoing project dealing with the construction of a private closed-end fund for the municipal area of Hannover, Germany. It is argued that for assessing the economic prospects of the project it is helpful to apply a Monte Carlo (MC) simulation approach. Thereby, it is possible to account for contamination risks. Questions that must be solved are (1) to find probability distributions for the uncertain variables and the correlations among these, (2) to adequately integrate legal and political parameters. Despite its merits with regard to accounting for contamination risks in investment appraisal a MC simulation may not be useful for every kind of risk. Integrating legal and political factors using a solely stochastic approach appears not to be convincing, since this kind of uncertainty results from the strategic interaction of agents. Therefore, the potential value of using game theory and institutional analysis is stressed.
This paper uses data from the German Socio-Economic Panel for the years 2000 to 2005 to study the earnings differential between self- and dependent employed German men. Constructing a counterfactual earnings distribution for the self-employed in dependent employment and using quantile regression decompositions we find that the earnings differential over the distribution cannot be explained by differences in endowments. Furthermore, low-earning self-employed could earn more in dependent employment. Finally, the observed earnings advantage for the self-employed at the top of the earnings distribution is not associated with higher returns to observable variables.
The paper demonstrates how the E–stability principle introduced by Evans and Honkapohja can be applied to models with heterogeneous and private information in order to assess the stability of rational expectations equilibria under learning. The paper extends already known stability results for the Grossman and Stiglitz model to a more general case with many differentially informed agents and to the case where information is endogenously acquired by optimizing agents. In both cases it turns out that the rational expectations equilibrium of the model is inherently E-stable and thus locally stable under recursive least squares learning.
Strong sustainability, according to the common definition, requires that different natural and economic capital stocks have to be maintained as physical quantities separately. Yet, in a world of uncertainty this cannot be guaranteed. To therefore define strong sustainability under uncertainty in an operational manner, we propose to use the concept of viability. Viability means that the different components and functions of a dynamic, stochastic system at any time remain in a domain where the future existence of these components and functions is guaranteed with sufficiently high probability. We develop a unifying and general ecological-economic concept of viability that encompasses the traditional ecological and economic notions of viability as special cases. It provides an operational criterion of strong sustainability under conditions of uncertainty. We illustrate this concept and demonstrate its usefulness by applying it to livestock grazing management in semi-arid rangelands.
Using panel data from Spain Farinas and Ruano (IJIO 2005) test three hypotheses from a model by Hopenhayn (Econometrica 1992): (H1) Firms that exit in year t were in t-1 less productive than firms that continue to produce in t. (H2) Firms that enter in year t are less productive than incumbent firms in year t. (H3) Surviving firms from an entry cohort were more productive than non-surviving firms from this cohort in the start year. Results for Spain support all three hypotheses. This paper replicates the study using a unique newly available panel data sets for all manufacturing plants from Germany (1995 – 2002). Again, all three hypotheses are supported empirically.
This paper contributes to the flourishing literature on exports and productivity by using a unique newly available panel of exporting establishments from the manufacturing sector of Germany from 1995 to 2004 to test three hypotheses derived from a theoretical model by Hopenhayn (Econometrica 1992): (H1) Firms that stop exporting in year t were in t-1 less productive than firms that continue to export in t. (H2) Firms that start to export in year t are less productive than firms that export both in year t-1 and in year t. (H3) Firms from a cohort of export starters that still export in the last year of the panel were more productive in the start year than firms from the same cohort that stopped to export in between. While results for West Germany support all three hypotheses, this is only the case for (H1) and (H2) in East Germany.
We use comparable micro level panel data for 14 countries and a set of identically specified empirical models to investigate the relationship between exports and productivity. Our overall results are in line with the big picture that is by now familiar from the literature: Exporters are more productive than non-exporters when observed and unobserved heterogeneity are controlled for, and these exporter productivity premia tend to increase with the share of exports in total sales; there is strong evidence in favour of self-selection of more productive firms into export markets, but nearly no evidence in favour of the learning-by-exporting hypothesis. We document that the exporter premia differ considerably across countries in identically specified empirical models. In a meta-analysis of our results we find that countries that are more open and have more effective government report higher productivity premia. However, the level of development per se does not appear to be an explanation for the observed cross-country differences.
Abstract: A recent survey of 54 micro-econometric studies reveals that exporting firms are more productive than non-exporters. On the other hand, previous empirical studies show that exporting does not necessarily improve productivity. One possible reason for this result is that most previous studies are restricted to analysing the relationship between a firm’s export status and the growth of its labour productivity, using the firms’ export status as a binary treatment variable and comparing the performance of exporting and non-exporting firms. In this paper, we apply the newly developed generalised propensity score (GPS) methodology that allows for continuous treatment, that is, different levels of the firms’ export activities. Using the GPS method and a large panel data set for German manufacturing firms, we estimate the relationship between a firm’s export-sales ratio and its labour productivity growth rate. We find that there is a causal effect of firms’ export activities on labour productivity growth. However, exporting improves labour productivity growth only within a sub-interval of the range of firms’ export-sales ratios.