Browsing by Subject "Productivity"

Now showing 1 - 9 of 9
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    Anthropogenic climate change has driven Lake Superior productivity beyond the range of holocene variability: an organic and stable isotopic study of Human impacts on a pristine biogeochemical system
    (2013-07) O'Beirne, Molly D.
    Recent studies have noted that changes in Lake Superior's physical, chemical and biological processes are apparent - including a warming of the surface waters at a rate twice as great as the surrounding airshed in the last 20 years. These changes are often difficult to perceive as cause for concern when not placed within a historical context. In this study, bulk C and N elemental abundance and stable isotope analysis of sediments from three piston and corresponding gravity cores, representing a record of lake-wide paleoproductivity trends spanning the Holocene, allows for the historical comparison with recent (1800 A.D. to present) productivity trends. Overall, Lake Superior experiences a slow, steady increase in productivity consistent with the concept of `natural' eutrophication, which is characterized by gradual increases in TOC and TON, as well as the steady 13C-enrichment of bulk sedimentary organic carbon and 15N-enrichment of bulk sedimentary organic nitrogen compositions. Over the last 200 years bulk concentrations and stable isotope compositions of carbon and nitrogen from eight multicores sampled at high resolution indicate that the Lake Superior basin has undergone productivity changes in the last two centuries (1800 to present) which are unique in the context of the Holocene. Overall, lake-wide sedimentary bulk organic proxy data show increasing primary production between 1900 and present, as indicated by an ~2 ‰ increase in δ13Corg. The most recent increases in productivity are likely a response to increasing water temperatures and longer stratified periods reported in Lake Superior. Down-core variations in the δ13C composition of algal-derived short-chain n-alkanes do not exhibit the same trend as that observed for bulk sedimentary organic matter (δ13Corg). The δ13C of bulk sedimentary organic matter shows systematic 13C-enrichment over the last ~9000 years, while the δ13C values of aquatic derived n-alkanes exhibit a systematic 13C-depletion to present-day. Down-core variation in δ13C values of n-alkanes likely reflect multiple isotope effects associated with carbon partitioning and fractionation associated with the biosynthesis of n-alkanes.
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    A bio-economic assessment of the spatial dynamics of U.S. corn production and yields
    (2012-02) Beddow, Jason Michael
    This dissertation reports on an investigation into the effects of location on corn production and productivity. The landscape of crop production is dynamic--where crops are produced changes dramatically over time. The answers to important questions about the potential impacts of global climate change and whether agriculture will be able to meet the world's increasing need for food are affected by the moving footprint of production. However, most studies of agricultural productivity and the effects of global warming do not consider that agriculture moves, and that the concomitant changes in natural services have important effects. A full set of county-level census data on corn production and area in the United States have been digitized and assembled for the first time, and new methods have been applied to account for changing geopolitical boundaries. Concepts adapted from economic index number theory are used to show that some 15 to 20 percent of the change in U.S. corn output over the past 130 years has come about due to shifts in where corn is produced. A newly developed, long-run, corn-specific weather dataset is used with the county data to show that, because of changes in the location of production, U.S. corn is now grown in cooler climates than it was a century ago, possibly offsetting some of the potential impacts of climate change. Finally, methods from ecological modeling, spatial econometrics, and crop modeling are combined to create a corn yield model that is then used to develop a location- and season-specific crop suitability indicator that takes into account the intra-seasonal dynamics of weather and the complex relationships between weather and yields. It will be shown that the suitability metric developed in this study gives results that are both consistent and more interpretable than more traditional approaches.
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    Essays on Government Policy and Productivity
    (2019-07) Dinerstein Madenfrost, Marcos
    This dissertation studies the effects of government policy on aggregate productivity by studying how government policy affects the allocation of resources across firms. Chapter 1 describes the data used in the following chapters. importantly, this data set is a plant level census of the manufacturing sector in Chile which allows to study government policy while taking into consideration firm heterogeneity. Chapter 2 was written jointly with Fausto Patiño Peña. It quantifies the effect of effective corporate tax rates on aggregate TFP through allocative efficiency. First, using the data described in Chapter 1 for the years 1998 to 2007 several characteristics of the effective tax rate distribution are documented. Two important findings are a large dispersion in the effective tax rate faced by firms and a mass of firms with a 0 percent tax rate. Next, these features are incorporated into a standard monopolistic competition model with capital and output wedges, where firms endogenously choose the tax rate they face. The model is then calibrated and the main finding is that if there were no corporate taxes in the economy, TFP would increase between 4 and 11 percent. Afterward, the effects of imposing the same tax rate on all firms are studied. A monotonically decreasing relationship between the level of the flat tax rate and TFP is found. Finally, Chapter 3 studies the interaction between financial frictions and firing costs and its effects on allocative efficiency and aggregate productivity. In particular, it quantifies the effect on aggregate productivity of an improvement in financial development in economies with firing costs. To do this, a small open economy model with heterogeneous firms that face collateral constraints and have to pay firing costs is developed. The model is then calibrated using the data described in Chapter 1. The main finding is that aggregate productivity increases by 2.5 percent following a financial reform that makes Chile's level of financial development comparable to that of the United Kingdom.
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    Essays on the economics of food production and consumption in Vietnam.
    (2008-12) Vu, Linh Hoang
    This study aims to provide an in-depth understanding of the economics of food production and consumption in Vietnam. Specifically, the study is comprised of five essays, covering several aspects of agriculture and food consumption in Vietnam. The first essay studies agricultural productivity growth in Vietnam, using province-level data. It concludes that total factor productivity (TFP) growth in agriculture contributed greatly to Vietnam's agricultural success after it adopted reform policies. However, TFP growth has slowed in recent years, despite significant output growth. The second essay examines the productive efficiency of rice farming households in Vietnam, using two methods, Data Envelopment Analysis (DEA) with bootstrap and Stochastic Frontier Analysis (SFA). It points out that there is variation in efficiency estimates across regions in Vietnam. Moreover, technical efficiency is significantly influenced by primary education and regional factors. The third essay estimates household food demand parameters in Vietnam, based on a recent household survey conducted in 2006. The results indicate that that food consumption patterns in urban and rural areas, and across regions and income groups, are quite different. This implies that targeted food policies should be formulated based on the specific food demand patterns of those groups. Socio-economic factors such as household size and composition, as well as the age of the household's head and education, have sizeable and statistically significant effects on food consumption. The fourth essay focuses undernutrition and food security in Vietnam. The income elasticity of calorie consumption is estimated using both parametric and non-parametric regressions. The finding of positive and significant calorie-expenditure elasticity implies that income growth can alleviate undernutrition Finally, the fifth essay examines the impacts of rising food prices on poverty and welfare in Vietnam. Increases in food prices raise the real incomes of those selling food, but make net food purchasers worse off. Overall, the net impacts on an average Vietnamese household's welfare are positive. However, the benefits and costs are not evenly spread across the population, so some households are made better off while the others are worse off.
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    Essays On Trade And Productivity
    (2018-05) Chan, Mons
    This dissertation consists of two chapters. The first chapter extends economic theory and empirical methods to examine firm outsourcing decisions. Empirical models of production often impose input complementarity and rule out an extensive margin in the decision to "make or buy" inputs. This paper develops a simple model of production which generalizes the standard Cobb-Douglas approach and allows labor and intermediates of similar types (or "tasks") to be complements, substitutes, or (importantly) outsourced entirely. Modeling this make-or-buy decision directly allows me to correct for the selection bias resulting from the endogenous outsourcing decision and to characterize the extensive margin of factor demand. I take the model to unique Danish data on task-level purchases of disaggregated labor (e.g., truck drivers), goods, and services (e.g., shipping) and find that labor and intermediates are gross substitutes. Estimated elasticities of substitution range from 1.5 to 4, with positive cross-price elasticities between 0 to 2 across inputs and industries. These results also hold in standard firm data using total labor and intermediate expenditure variables. Aggregating across firms, I show that demand for labor is becoming increasingly price elastic over time, driven by growing outsourcing and specialization. To illustrate the importance of allowing for flexible substitutability, I examine the effect of an increase in minimum wages in the Danish manufacturing industry, finding that ignoring outsourcing underestimates disemployment by 40%. This finding also has important implications for estimating productivity. I estimate the effect of recent decreases in Danish import tariffs on firm productivity and show that controlling for substitution triples the results relative to benchmark models which only control for price effects. In the second chapter, my coauthor, Ming Xu, and I investigate how trade costs and firm make-or-buy decisions have an impact on the aggregate wage distribution. Firms react to changes in factor prices with intensive and extensive-margin employment adjustments at the occupational-level. We study the distributional and aggregate consequences of this make-or-buy dynamic by developing a novel network model of heterogeneous firm-to-firm trade where the boundary of each firm depends on factor prices and firm-occupation comparative advantage in input-production. We show that the model can be easily aggregated and taken to industry-level data, and use the calibrated model to examine recent trends in employment, wages and trade in the USA. We use public OES and CPS data to show empirical evidence that a significant fraction of the growth in wage inequality in the USA is due to changes in firm/industry specialization and occupation sorting. To understand and measure the underlying causes of these trends, we calibrate the model to occupation and industry data from the OES and input-output tables. The results suggest that 1/3rd of the increases in wage inequality stem from decreases in inter-industry trade frictions with the remaining 2/3rds stemming from changes in technology and labor supply. Falling trade frictions are also responsible for all of the increases in occupational sorting and concentration. Had trade frictions been held at their 2002 level, productivity growth would have led to an increase in vertical integration, rather than the decrease observed in the data.
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    An evaluation of sitting time and physical inactivity on back pain and productivity loss among services sector workers
    (2014-01) Briggs, Anna
    Within the workplace, the relationship between sedentary behaviors and back pain, and the impacts on worker productivity remain unclear. Data from a 2010 employee health assessment survey was utilized to evaluate the impact of sitting time and physical inactivity on back pain and productivity loss in a sample of public administration industry (e.g., services sector) workers. Directed Acyclic Graphs (DAGs) informed multivariate logistical models within two cross-sectional studies that 1) established a sedentary risk profile for back pain and 2) evaluated the interactive effect of physical inactivity and sitting on back pain and productivity loss. Results from this study suggest that both non-modifiable factors, such as age, gender, education, and job classification, and modifiable factors, such as sedentary behaviors, high BMI and tobacco use, are important when designing health promotion programs to prevent and treat back pain in a working population. Results also suggest that prolonged sitting time has an interactive effect with physical inactivity, and therefore, when assessing risk in an employee population, employers should consider both physical activity and sedentary exposures at work and during leisure to gain a complete understanding of total worker exposures. Results support the National Institute for Occupational Safety and Health's Total Worker HealthTM strategy by informing the direction of future research aimed at utilizing health risk assessment screening tools for occupational back pain and interventions that extend healthy lives of workers and reduce the burdens of illness and disability.
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    Faculty research productivity at Assumption University Thailand
    (2014-10) Pornsalnuwat, Pavinee
    The purpose of this study is to determine the factors associated with faculty's perceptions of their roles as researchers at a Thai private university, Assumption (AU). In recent decades there has been a dramatic increase in the size of Thailand's higher education sector reflecting both the trends of massification and privatization. One of Thailand's leading private universities is Assumption with a new world-class campus located in Bang Na near the new Bangkok international airport.The university is Thailand's first international university and grew out of Assumption College (an elite private Catholic P-12 school) and ABAC (a highly successful business college and university). The institution has a long tradition of attracting top students and offering them a quality education that prepares them well to join the elite in business, government, and academic sectors. Despite the rapid growth of Thai higher education, Thai universities do not fare well in international ranking systems. The major reason is the lack of research productivity of Thai faculty in higher education. It is a key assumption of this dissertation that effective research and development contribute to national productivity and competitiveness.In this research the methodology is case study research and there is the use of triangulated qualitative research methods including extensive document analysis and interviews with diverse stakeholders such as AU administrators and faculty. Also interviewed are national and international experts knowledgeable to the Thai higher education landscape. A total of individuals were interviewed with a 100% response rate. Overall, it is found that research productivity is highly skewed with a small number of faculty actively engaged in research, while the majority are much less active or inactive. A tetrahedron model is used to reflect the four key factors found to influence the productivity of faculty, namely, 1) motivation and incentives, 2) resources, 3) skills, and 4) Thai politics and culture. Various suggestions are presented to enhance research productivity at AU such as the development of a long-term plan to give greater priority and resources to research. The plan would include activities such as special training and grant development workshops, mentoring, hiring outstanding faculty with proven research records, and the promotion of research collaboration with international scholars. The "triple helix model" is also presented reflecting the need for much greater cooperation among the business, government, and academic sectors in conducting and impactful and innovative research.The data presented in this dissertation indicate that Thailand in general and AU in particular are not realizing their R & D potential. This places Thailand at risk in terms of what has been termed the middle income trap (Gill & Kharas, 2007). Thus, as many countries such as Japan and Korea developed industrial policies, Thailand critically needs a national research policy to foster excellence in research, particulary quality applied research which will enhance Thailand's national competitivenss and facilitate its escaping the middle income trap. The designation of nine institutions as research universities is a step in the right direction. Assumption University, a private institution and Thailand's first international university, with its strong Catholic heritage of ethics and teaching and its new world-class campus, has also the potential to strengthen its research profile to enhance even more the quality of its teaching and learning environment. For that goal to become a reality, AU must give higher priority to creating a favorable academic research climate with increased funding and incentives for doing useful impactful research.
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    Landscape productivity and the ecology of brood division in Golden-winged Warblers in the Western Great Lakes Region
    (2014-08) Peterson, Sean Michael
    Using radio-telemetry of fledgling Golden-winged Warblers (Vermivora chrysoptera) in the western Great Lakes region from 2010-2012, I investigated the poorly understood behavior of brood division. Brood division occured when both males and females care for a brood after fledging. I observed female-reared subbroods traveling over twice as far from the natal patch and nest sites as male-reared subbroods. The difference in space use we observed was correlated with female-reared subbroods preferentially moving in similar directions for a three-day period in which male-reared subbroods maintained an area of use. Because parental strategies differ between sexes with regard to movement patterns, I suggest incorporating the differences in space use between sexes in future management plans for Golden-winged Warblers and other species that employ brood division. Specifically, management actions might be most effective when they are applied at spatial scales large enough to incorporate the habitat requirements of both sexes throughout the entire reproductive season. Additionally, I developed a method for estimating productivity of a breeding season based on landscape around any given point. I used logistic exposure models to identify the influence of landscape structure and composition on nest productivity and fledgling survival. I used those models to predict spatially-explicit, full-season productivity across my study sites to identify areas of low relative productivity that could be targeted for management. I then used my models of spatially-explicit, full-season productivity to simulate the impact of potential management actions on my study sites with the goal of increasing total population productivity. I concluded that spatially-explicit, full-season productivity models that incorporate data from both the nesting and post-fledging periods are useful for informing breeding habitat management plans for Golden-Winged Warblers and that similar models can benefit management planning for many other species of conservation concern.
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    Survival and habitat use by post-fledging forest-nesting songbirds in managed mixed northern hardwood-coniferous forests.
    (2010-10) Streby, Henry M.
    Until recently, studies of breeding migratory songbirds have been primarily limited to the nesting season. Therefore, there is very little information about songbird survival and habitat use during the post-fledging period (i.e. the time between nesting and fall migration) available to those making management decisions. I expanded on the traditional nest-monitoring study and used radio telemetry to monitor survival and habitat use of fledgling songbirds in managed northern hardwood-coniferous forests of northern-Minnesota. In addition, I used mist-nets to sample use of early-successional forest stands (regenerating clearcuts) and forested wetlands by mature forest-nesting birds during the post-fledging period. I found that many assumptions of songbird nesting studies are unreliable, including the common assumption that the presence of a family group is confirmation of a successful nest in an occupied territory. In addition, I found that annual fledgling survival can vary considerably, and does not vary consistently with nest productivity, a finding with broad implications for models of songbird population growth. Furthermore, I found that habitat used by birds during the post-fledging period can be considerably different than that used for nesting, and that post-fledging habitat use can affect fledgling survival. In addition, I found that factors commonly affecting nest productivity (e.g. edge effects) can affect fledgling survival differently. From mist-netting, I found that many mature-forest birds used non-nesting cover types during the post-fledgling period, but most of that use was by only a few species, and hatch-year birds rarely used non-nesting cover types before independence from adult care. Models of capture rates in non-nesting cover types indicated that use of non-nesting cover types by mature-forest birds was primarily related to food availability and secondarily to cover in the form of relatively dense vegetation. My results indicated that nearly every conclusion made about breeding population ecology of mature-forest birds based only on nesting data was contradicted by data from the post-fledging period. My results clearly demonstrate that data from the entire breeding season (nesting and post-fledging) are necessary to understand songbird seasonal productivity and habitat associations.