1,721,197 research outputs found
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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Empirical Analyses in Agricultural and Resource Economics
Full text linkAgriculture has played a profound and unique role in humanity's development. We are dependent on agriculture for the vast majority of our food supply, and have so far been successful at increasing agricultural production to meet rising demand. At the same time, agriculture is the largest and most direct way that humans have altered our planet's landscape and natural environment. Indeed, over half of all land in the United States is used for some agricultural purpose. In this dissertation, I explore three different aspects of human-environmental-agricultural interdependency in the United States. In the first chapter, I study agricultural workers' wage-responsiveness under different environmental conditions on California blueberry farms. In the second chapter, Fiona Burlig and I study the effect of human social networks on agricultural technology adoption in three upper-Midwestern states. Finally, in the third chapter, I study how the location of ethanol refineries in the US Corn Belt affects crop choice decisions and nutrient runoff. Each of these chapters highlights a different interaction between human economic systems (wages, social networks, renewable fuel policy), environmental conditions (temperature, nitrogen application/runoff), and agricultural enterprises (specialty crop labor productivity, adoption of fertilizer, crop rotations). I utilize a similar empirical strategy in each chapter, employing fixed effects and other panel data techniques to control for time-invariant determinants of productivity, technology adoption, and optimal crop choice, respectively. This dissertation highlights the benefits of panel data methods in agriculture, especially in the modern era of abundant micro-level data.In the first chapter, I study how agricultural laborers' productivity responds to changes in the piece rate wage they are paid: a wage paid per unit of output rather than per unit of time. Specifically, I exploit quasi-experimental variation to estimate the elasticity of labor productivity with respect to piece rate wages by analyzing a high-frequency panel of over 2,000 blueberry pickers on two California farms over three years. To account for endogeneity in the piece rate wage, I use the market price for blueberries as an instrumental variable. I find that picker productivity is very inelastic on average, and I can reject even modest elasticities of up to 0.7. However, this average masks important heterogeneity across outdoor working conditions. Specifically, at temperatures below 60 degrees Fahrenheit, I find that higher piece rate wages do in fact induce increases in labor productivity. This is suggestive evidence consistent with a model where at moderate to hot temperatures, workers face binding physiological constraints that prevent them from exerting additional effort in response to higher wages. This insight has important implications for understanding how climate change will affect the agricultural labor sector.In the second chapter, Fiona Burlig and I use historical data and a natural experiment to study the effect of social networks on agricultural technology adoption. We present a model of the effects of social network size on information and technology take-up and test its implications using a unique natural experiment in the mid-20th century US Midwest. We find that social network expansions, in the form of mergers between congregations of the American Lutheran Church, led to increased rates of agricultural technology adoption among farmers. In counties that experienced a merger, the number of farms using nitrogen fertilizer increased by over 7% and the total fertilized acreage increased by over 13% relative to counties without a merger. We provide evidence that these effects are driven by increased information sharing between farmers as a result of these congregational mergers.In the third chapter, I study how the location of ethanol refineries within the US Corn Belt affects farmers' land use decisions. Ethanol production in the United States, driven by federal renewable fuel policy, has exploded over the past two decades and has prompted the construction of many ethanol refineries throughout the US Corn Belt. These refineries have introduced a new inelastic demand for corn in the areas where they were built, reducing basis for nearby farmers and effectively subsidizing local corn production. I explore whether and to what extent the construction of new ethanol refineries has actually increased local corn acreage. I also explore some environmental effects of this acreage increase. Using a thirteen year panel of over two million field-level observations in Illinois, Indiana, Iowa, and Nebraska, I estimate a net increase of nearly 300,000 acres of corn in 2014 relative to 2002 that can be attributed to the placements of new ethanol refineries. This increase comprises approximately 0.75% of the total 2014 corn acreage within my dataset. Furthermore, this effect is separate from the general equilibrium effect of ethanol policy increasing aggregate demand for corn. Back-of-the-envelope calculations suggest that over 21,000 tons of the nitrogen applied to fields in my sample in 2014 can be attributed to refinery location effects. Essentially all of these observed effects occur only in areas within 30 miles of an ethanol refinery, suggesting that refineries have meaningful localized impacts on land use and environmental quality such as nitrate runoff
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Systemic Risk and Returns
Full text linkI solve a consumption based model, with interfirm systemic risk, for a portfolio optimization with arbitrary return distributions and endogenous stochastic discount factor (sdf). The model highlights a new systemic risk: systemic allocation risk. In contrast to the case without systemic risk, the market and planner allocate capital differently. The externality causes the planner to reduce investment in the risky firm. The market, modeled as a representative agent, does not just ignore the externality and invest as if there were none. Instead, systemic risk increases the representative agent's investment in the systemically risky institution or industry, further increasing systemic risk. I introduce bailout of the financial industry and find it has a beneficial direct effect and a distortion effect. In some cases, investor moral hazard can make ex post optimal bailouts reduce ex ante utility - even when bailout does not benefit the financial industry's investors. I show that systemic risk, as opposed to systematic risk, can be characterized as a situation where the fundamental theorems of asset pricing do not apply.Next I put the the model into a factor model, using the arbitrage pricing theory for market pricing of the firms. I use the model to distinguish between systematic and systemic risks. By directly including systemic risk, the potential of an interfirm or inter-industry externality, the model shows that including terms with fat tails in specifications for returns does not make them systemic risk if they still meet the definition of systematic risk (Systematic risk is risk within a firm's returns that is both non-causal and correlated with the stochastic discount factor - and therefore undiversifiable. In a factor model, systematic risk in the financial industry is the overall magnitude of firms loading onto systematic factors. The systematic factors do not need to be Gaussian.). The model shows why systematic risk is so often mistaken as systemic risk, why systematic risk in the financial industry is important, and why it should be considered along with systemic risk in regulatory efforts. The model is then used to delineate and outline the various types of risk. This vocabulary can facilitate communication and research in systemic risk. Finally, I derive a popular systemic risk measure directly in terms of the parameters of a pricing model. I test the one that attempts to include causality in its measure, CoVaR.CoVaR seeks to use joint return data to measure a firm's contribution to systemic risk. To learn what comprehensive regulatory changes can do to systemic risk in general, and CoVaR in particular, Part 4 estimates the impact of the extensive and coincident U.S. regulatory changes of 1993 (including Prompt Corrective Action law and Basel I) on the systemic risk level of commercial banks, as measured by CoVaR. Investment banks not subject to the law are used as controls. In a difference-in-difference framework, the law is used as a treatment shock. Use of a novel CoVaR measure (unconditional rolling CoVaR) allows econometric assessment of exogenous changes and estimation of CoVaR standard errors. With high power, no effect is found. This eliminates from possibility one of two formerly widely held beliefs that are each the basis of a literature: 1. That PCA and concurrent regulation lowered systemic risk, or 2. That CoVaR measures systemic risk. The unique circumstances used for this test could also be exploited to assess other systemic risk metrics or inform other risk/regulation questions
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Essays in Time Series Econometrics: Nonlinear, Nonstationary GMM Estimation, Credit Shock Transmission, and Global VAR Models
Full text linkThis dissertation consists of three chapters dealing with different topics in time series econometrics including generalized method of moments (GMM) estimation and vector autoregressions (VAR). These econometric models have revolutionized empirical research in macroeconomics. Previous work by Hansen and Singleton (1982) showed that the GMM method can be applied to estimate nonlinear rational expectations models in a simple way that the models need not even be solved. The seminal work of Sims (1980) has demonstrated how VAR models can be used for macroeconomic forecasting and policy analysis. The objective of this dissertation is to provide some new econometric tools for applied research in macroeconomics using time series data.The first chapter develops an asymptotic theory for the GMM estimator in nonlinear econometric models with integrated regressors and instruments. We establish consistency and derive the limiting distribution of the GMM estimator for asymptotically homogeneous regression functions. The estimator is consistent under fairly general conditions, and the convergence rates are determined by the degree of the asymptotic homogeneity of regression functions. Similar to linear regressions, we find that the limiting distribution is generally biased and non-Gaussian, and that instruments themselves cannot eliminate the bias even when they are strictly exogenous. Therefore, GMM yields inefficient estimates and invalid - and chi-square test statistics in general. By implementing the fully modified method developed by Phillips and Hansen (1990), we obtain an efficient GMM estimator which has an unbiased and mixed normal limiting distribution.In the second chapter, we develop a novel shock identification strategy in the context of two-country/block structural vector autoregressive (SVAR) models to identify the transmission of credit shocks. Specifically, we investigate how credit shocks originating in the U.S. or euro area affect domestic economic activity in emerging Asia. Shocks within each block are identified using sign restrictions, whereas shocks across the two blocks are identified using a recursive structure (block Cholesky decomposition). This strategy not only enables us to distinguish the external credit shock from the other structural shocks, but also captures the responses of the domestic country. The main findings include that the transmission of credit shocks across countries through the channel of credit contagion is fast and protracted. The adverse effects of external credit tightening are mitigated by domestic credit policy easing in China, but lead to significant decreases in credit and GDP growth in the other emerging Asian countries. We also find that the external credit shocks play a non-negligible role in driving economic fluctuations in emerging Asia, although the role is smaller in China.In the last chapter, we use a global vector autoregressive (GVAR) model to forecast the principal macroeconomic indicators of the original five ASEAN member countries (i.e. Indonesia, Malaysia, Philippines, Singapore, and Thailand). The GVAR model is a compact model of the world economy designed to explicitly model the economic and financial interdependencies at national and international levels. Our GVAR model covers twenty countries which are grouped into nine countries/regions. After applying vector error correction model (VECM) to estimate parameters in the GVAR, we generate twelve one-quarter-ahead forecasts of real GDP growth, inflation, short-term interest rates, real exchange rates, real equity prices, and world commodity prices over the period 2009Q1-2011Q4, with four out-of-sample forecasts during 2009Q1-2009Q4. Forecast evaluation based on the panel Diebold-Mariano (DM) tests shows that the forecasts of our GVAR model tend to outperform those of country-specific VAR models, especially for short-term interest rates and real equity prices. These results suggest that the interdependencies among countries in the global financial market play an important role in macroeconomic forecasting
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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Essays on the Economics of Energy and the Environment
Full text linkThis dissertation explores two aspects of environmental economics and the evaluation of energy policies in the buildings sector. The first chapter focuses on energy standards, and the second chapter focuses on green labels.The first chapter assesses whether commercial real estate market participants are willing to pay a premium for an energy efficient building that has not received a green label. I utilize a unique dataset of detailed building-level observations and a spatial semiparametric matching framework that exploits quasi experimental state-by-year variation in the implementation of mandatory building energy codes, to estimate selling price and rent premiums for a more stringent code. I find that buildings constructed under a more stringent energy code are associated with rent and selling price premiums of approximately 2.7% and 10%, respectively, compared to buildings constructed just before the code came into effect. When tenants pay directly for utilities, buildings constructed under an energy code are associated with 5.7% higher rents. While building energy codes have been promoted to address landlord-tenant informational asymmetries that would not be addressed by a carbon pricing strategy, these estimated premiums are consistent with complete capitalization of estimated building-level savings, and as such they cast doubt on the existence of an energy efficiency gap resulting from adverse selection between landlords and tenants. In the second chapter, I assess whether nonrandom selection affects the frequently-touted benefits of green-labeling policies in the commercial building stock. While green-labeled buildings have been found to sell at a premium compared to nearby controls with similar observable characteristics, the voluntary nature of the labeling decision implies green-labeled buildings may have different unmeasured characteristics that may account for at least a portion of the premium. Therefore, it is unclear whether green-labeled building premiums are a causal effect of the labels. I use data on repeat sales transactions and detailed hedonic characteristics to test whether green-labeled office buildings were selling at a premium before they were labeled, and combine these results with post-labeling price premium estimates to identify realized cost-benefit ratios for green-labeling policies. The data suggest the causal net benefits of green labels range from 19.95 per square foot. The estimated net benefits are smaller than previous estimates that have focused solely on the benefits and ignored the potential biases from nonrandom selection
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Essays on Environmental and Resource Economics
Full text linkThis dissertation consists of three applied essays on environmental and resource economics. The essays study consumer and local government responses to exogenous shocks: randomized environmental messages, variation in international mineral prices and a widely publicized food-borne disease outbreak. In particular, this dissertation focuses in three broad areas: (i) investigating whether environmental messages can increase energy efficient technology adoption by poor populations and understanding the characteristics of the individuals who respond to these messages, (ii) testing whether increases in municipal income translate into additional environmental investments and policies in developing countries and, (iii) studying the role of food borne disease outbreaks on consumer purchases and preferences
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
An Analysis of the World’s Environment and Population Dynamics with Varying Carrying Capacity, Concerns and Skepticism
Full text linkDue to the open-access nature of the environment we consider an ad hoc adjustment of people’s footprints to the quality of the environment. The adjustment is due to concerns, but hindered by skepticism about announced changes in the state of the environment. Changes in the quality of the environment affect Earth’s carrying capacity. By expanding the Lotka-Volterra predator-prey model to include these features we show that despite skepticism the environment-population system does not collapse. We also show that in the ideal case of no skepticism, the interplay between the non-optimally changing environmental concerns and carrying capacity sends the world’s environment and human population on an oscillating course that leads to a unique interior steady state. These results require no further technological, social or international progress.Environment; Population; Carrying Capacity; Concerns; Skepticism
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