Para medir o impacto de mudanças climáticas, acompanhadas variações do investimento agrícola, sobre a atividade agrícola brasileira, foram estimadas conjuntamente funções de receita e de custo de produtos e insumos agrícolas. Estas foram derivadas de uma função de lucro restrita, condicional a variáveis de clima e investimento. A pesquisa inova pela metodologia, diferente das demais empregadas anteriormente para o caso brasileiro, pela maior precisão dos dados de clima e pela inclusão do investimento agrícola como variável de mitigação dos efeitos gerados pela variação climática. Os resultados mostraram uma redução da lucratividade agrícola para o Brasil com o aumento da temperatura e precipitação no longo prazo, apesar de variarem conforme regiões. Saíram beneficiadas regiões mais ricas, em detrimento das mais pobres, cuja maior parte da produção agrícola é voltada para a subsistência. O investimento agrícola atuou como redutor desta tendência, de crescimento da desigualdade agrícola, ajudando a reverter apenas parcialmente o efeito do aquecimento. / To measure the impact of climate changes along with changes in agricultural investments in Brazil\'s agricultural sector, this paper jointly estimates revenue functions for the outputs and cost functions for the inputs. These equations were derived from a restricted profit function conditional to climate and investment variables. The paper innovates by using the profit function approach to study Brazils agricultural sector. It also brings more precise data and adds investment as a relevant variable in the model. Results show a reduction in profitability as temperature and precipitation grow, but they are not homogeneous amongst the different regions. Richer regions seem to do better than the poor ones, which have a large part of their production focused on subsistence. Investment seems to act as a counterbalance to this trend of increasing agricultural inequality, partially reverting the global warming effects.

Para medir o impacto de mudanças climáticas, acompanhadas variações do investimento agrícola, sobre a atividade agrícola brasileira, foram estimadas conjuntamente funções de receita e de custo de produtos e insumos agrícolas. Estas foram derivadas de uma função de lucro restrita, condicional a variáveis de clima e investimento. A pesquisa inova pela metodologia, diferente das demais empregadas anteriormente para o caso brasileiro, pela maior precisão dos dados de clima e pela inclusão do investimento agrícola como variável de mitigação dos efeitos gerados pela variação climática. Os resultados mostraram uma redução da lucratividade agrícola para o Brasil com o aumento da temperatura e precipitação no longo prazo, apesar de variarem conforme regiões. Saíram beneficiadas regiões mais ricas, em detrimento das mais pobres, cuja maior parte da produção agrícola é voltada para a subsistência. O investimento agrícola atuou como redutor desta tendência, de crescimento da desigualdade agrícola, ajudando a reverter apenas parcialmente o efeito do aquecimento. / To measure the impact of climate changes along with changes in agricultural investments in Brazil\'s agricultural sector, this paper jointly estimates revenue functions for the outputs and cost functions for the inputs. These equations were derived from a restricted profit function conditional to climate and investment variables. The paper innovates by using the profit function approach to study Brazils agricultural sector. It also brings more precise data and adds investment as a relevant variable in the model. Results show a reduction in profitability as temperature and precipitation grow, but they are not homogeneous amongst the different regions. Richer regions seem to do better than the poor ones, which have a large part of their production focused on subsistence. Investment seems to act as a counterbalance to this trend of increasing agricultural inequality, partially reverting the global warming effects.

This thesis provides a bridge between two strands of efficiency literature. As we describe in the first part, the theory of efficiency is generally focused on equilibrium and mild devia- tions from it. In contrast, empirical studies document large variations in efficiency that are persistent in real economies. We describe two theoretical concepts as driving forces behind fluctuating performance of companies. Firstly, efficiency is derived from competition and is dynamic by its nature. As production happens in time, changing supply and demand conditions induce the ne- cessity to continuously adjust production processes. These changes are implemented under conditions of uncertainty, which directly leads to regular inefficiencies, implying that out- of-equilibrium situations are normal rather than rare. Secondly, standard models typically rely on price exogeneity to separate technical and allocative components of overall economic efficiency. We point out that this assumption is likely to fail due to extreme heterogeneity of the units of analysis. We elaborate in detail on the significance of heterogeneity in efficiency models, especially the heterogeneity of capital. As a result we demonstrate how various combinations of heterogeneous assets imply further swings in efficiency. We show that integrating both...

The ongoing financial crisis has had major adverse impact on the credit market. As the financial crisis progresses, the skyrocketing unemployment rate puts more and more customers in such a position that they cannot pay back their credit debts. The deteriorating economic environment and growing pressures for revenue generation have led creditors to re-assess their existing portfolios. The credit re-assessment is to accurately estimate customers' behavior and distill information for credit decisions that differentiate bad customers from good customers. Lending institutions often need a specific rule for defining an optimal cut-off value to maximize revenue and minimize risk. In this dissertation research, I consider a problem in the broad area of credit risk management: the selection of critical thresholds, which comprises of the "optimal cut-off point" and an interval containing cut-off points near the optimal cut-off point (a "near-optimal interval"). These critical thresholds can be used in practice to adjust credit lines, to close accounts involuntarily, to re-price, etc. Better credit re-assessment practices are essential for banks to prevent loan loss in the future and restore the flow of credit to entrepreneurs and individuals. The Profit Function is introduced to estimate the optimal cut-off and the near-optimal interval, which are used to manage the credit risk in the financial industry. The credit scores of the good population and bad population are assumed from two distributions, with the same or different dispersion parameters. In a homoscedastic Normal-Normal model, a closed-form solution of optimal cut-off and some properties of optimal cut-off are provided for three possible shapes of the Profit Functions. The same methodology can be generalized to other distributions in the exponential family, including the heteroscedastic Normal-Normal Profit Function and the Gamma-Gamma Profit Function. It is shown that a Profit Function is a comprehensive tool in the selection of critical thresholds, and its solution can be found using easily implemented computing algorithms. The estimation of near-optimal interval is developed in three possible shapes of the bi-distributional Profit Function. The optimal cut-off has a closed-form formula, and the estimation results of near-optimal intervals can be simplified to this closed-form formula when the tolerance level is zero. Two nonparametric methods are introduced to estimate critical thresholds if the latent risk score is not from some known distribution. One method uses the Kernel density estimation method to derive a tabulated table, which is used to estimate the values of critical thresholds. A ROC Graphical method is also developed to estimate critical thresholds. In the theoretical portion of the dissertation, we use Taylor Series and the Delta method to develop the asymptotic distribution of the non-constrained optimal cut-off. We also use the Kernel density estimator to derive the asymptotic variance of the Profit function. / Statistics

The thesis consists of four papers. The first two essays deal with entry externalities, the third studies the Law of One Price (LOP), while the last essay examines average profits for a monopolist under uncertainty. In the first essay, entry externalities in the form of information and positive payoff externalities are studied. When a firm enters a market, it often imposes externalities on existing firms and/or future potential entrants. If products are substitutes, these externalities are typically negative; if products are complements, the externalities are typically positive. Externalities related to substitution or complementarities between products are called payoff externalities, since entry by one firm has a direct effect on the other firms' payoff. Another type of externality arises when firms have private information about the profitability of entry. In this case, the entry decision of one firm potentially reveals that firm's private information. The focus of the paper is on the scope for intervention for an uninformed social planner, when firms privately know the profitability of entry and moreover, the firms have an option to delay their entry. The main result is that there is insufficient entry, since firms delay too much in equilibrium and further, the social planner can increase welfare by subsidizing early entry. Continuing on this theme, the second essay has the same focus, but instead takes the time of entry as fixed, while generalizing the analysis of payoff externalities also to the case of negative payoff externalities. The main contribution is the characterization of equilibria under both positive and negative payoff externalities and the implications for public policy. Here, the scope for intervention will, in contrast to the results in the first essay, be low, when entry is profitable for uninformed firms. In the third essay (joint with Richard Friberg), deviations from the LOP are studied in the presence of transport costs, under the assumption that firms can endogenously choose to segment markets in order to prevent arbitrage by consumers. It is shown that the deviation from LOP can increase as transport costs fall between countries. The last essay (joint with Richard Friberg), studies the problem facing a monopolist when the cost of inputs is uncertain. The main result is that the monopolist can gain from this uncertainty, in the sense that average profits are increasing in the variability of costs. / Diss. Stockholm : Handelshögsk., 2001