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El texto completo de este trabajo no está disponible en el Repositorio Académico UPC por restricciones de la casa editorial donde ha sido publicado. / Empirical methods play an important role in the field of geomechanics due to the recognized complexity of the nature of rock mass. This study aims to analyze the applicability of empirical design methods in vein-shaped hydrothermal mining deposits (narrow vein) using Bieniawski and Barton classification systems, Mathews stability graphs, Potvin and Mawdesley geomechanics classification systems, and mining pit dilution based on the equivalent linear overbreak/slough (ELOS). In most cases, these methods are applied without understanding the underlying assumptions and limits of the database in relation to the inherent hidden risks. Herein, the dilutions obtained using the empirical methods oscillate between 8% and 11% (according to the frontal dimension), which are inferior to the operative dilution of the mine at 15%. The proposed model can be used as a practical tool to predict and reduce dilution in narrow veins.

The primary objective of this study was to develop demand equations at retail for selected Venezuelan food commodities. Commodities included for analysis were rice, refined sugar, crude sugar, flour, potatoes, beef, pork, black beans, corn, and powdered milk. The basic statistical technique employed in the analysis was least squares multiple regression. Although several mathematical forms for these demand equations were evaluated, a log-log transform was found to be most useful. Independent variables included own price, prices of substitutes and complements, time and income . Observations were taken from Venezuelan time series data over the period 1945-1965. Development of these basic demand equations facilitated the treatment of a second objective which was to evaluate the degree of complementarity and substitution between each one of the commodities included in the model. Further, it provided the necessary structural framework to give exante examination to selected policy alternatives for Venezuelan agriculture. Alternatives examined included minimwn price and import policies. Interesting results and conclusions may be s ummarized as follows: 1. Difficult statistical problems are encountered in an attempt to estimate direct and cross elasticities of demand from time series data . 2 . A less general approach utilizing principles of demand theory is advisable until further requirements are made in the data series. 3. A consistent demand model docs provide useful insights into the interrelationships of commodity demands in terms of direction of change in price and quantity if not in terms of their magnitude. 4. Regional and social stratification of price, income and consumption data should improve the reliability of any subsequent analyses . 5. Additional household expenditure surveys of a cross-sectional nature would provide useful and necessary checks on the demand estimates obtained from time series data.

In an environment of increasing government expenditures financed largely viii through taxes, including a relatively visible and large residential property tax, the issue of whether property taxes are capitalized into market values is increasingly important. Property tax capitalization is the reflection of property taxes in the value of real property. The capitalization of property tax does not necessarily pose a problem; rather, problems arise when homes identical to each other have different taxes and these differentials are then capitalized into market values. These capitalized tax differentials result in large capital gains and losses to owners of real estate. This study (1) reviews existing economic theory and empirical evidence on the capitalization of property taxes, (2) develops a model of property valuation inclusive of tax effects, and (3) estimates the parameters of this model using a comprehensive data set of over 334 home sales in the Logan, Utah area. The empirical results include an estimate of the tax capitalization effect. Two closely related issues are also addressed in the study. They include: (I) changes in real estate prices, including a suggested method for measuring such change and (2) a study of property tax equity, including two specific measures of tax fairness. The conclusions are (I) tax differentials are capitalized; (2) real estate prices in the study area increased approximately 10 percent per year from 1989 to 1992; and (3) there is significant variation in assessment ratios.

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<p> This thesis is an empirical exploration into a range of issues related to the economics of the utilization of physician services. Physicians play an important role in a health care system as physicians are a patient's primary point of contact with the health care system and physicians are predominantly responsible for directing how patients use other health care resources. In particular, physicians are at the center of Canada's universal public insurance system with first dollar coverage for medically necessary physician and hospital services.</p> <p> The thesis comprises three separate essays. The first essay has a methodological focus on statistically modeling and predicting the use of general practitioners (GPs) when use is measured as the number of GP visits. The essay compared a state-of-the-art parametric latent class negative binomial model to a nonparametric kernel conditional density estimator, and evaluated how well each was able to fit the observed data and predict physician use.</p> <p> The second and third essays look at more substantive policy questions. The second essay investigates how the supply of GPs and specialists affects the mix of physician services received by individuals. A persistent concern in many health care systems is how variations in the supply of physicians will impact the use of physician services. The results suggest concerns about concerns of patient access and receipt of care in the presence of a shortage of specialists may be mitigated, all else equal, if patients are able to substitute GP services for specialist services.</p> <p> The third essay examines income-related inequity in the use of physician services by asthmatics and diabetics, relative to the general population, and the contributions of different factors to income-related inequality using the concentration index approach.</p> / Thesis / Doctor of Philosophy (PhD)

<p> This thesis seeks to describe and explain the spatial pattern of urban residential blight. The empirical analysis is limited to one study area; that of the Chicago metropolitan area. The data are U.S. Census data for census tracts in 1940, 1950, and 1960. Following a review of pertinent literature, an attempt is made to conceptualise the process that generates residential blight. From this conceptual framework, a number of hypotheses are developed concerning the relationship between residential blight and selected socio-economic variables. Other relationships are derived from an interpretation of maps of residential blight in the Chicago area for the different time periods. The hypotheses are tested using such multivariate procedures as principal components analysis, and regression and correlation analysis. The thesis also contains an application of the Blalock-Simon procedure for causal modelling to the Chicago data. The findings of the empirical analysis are related to present knowledge concerning urban residential blight. </p> / Thesis / Doctor of Philosophy (PhD)

<p> The overall goal of this thesis is to provide a deeper understanding of the role of dynamic stochastic general equilibrium (DSGE) models as foundations upon which empirical work is conducted. This is a very broad topic with a large existing literature. For this purpose, my dissertation focuses on applying the tools and rich structure of DSGE models to answer questions that have hitherto been studied only by using a reduced-form characterization. I have chosen to look at two specific macroeconomic questions of interest: the economic consequences of oil price shocks in Canada and the role of intangible capital (IC) in explaining cyclical dynamics of S&P500 earnings. Chapter 2 look at the economic consequences of oil price shocks in a structural vector autoregressions (VAR) framework. Chapter 3 builds on this by developing an open economy DSGE model to investigate the impact of oil price shocks on the aggregate Canadian economy and to quantify the relative contribution of U.S. and Canadian monetary policy in transmitting oil price shocks. Chapter 4 studies another interesting macroeconomic phenomenon: the excess volatility of aggregate profits. We embed intangible capital into an otherwise standard real business cycle (RBC) model to examine the role of intangible capital in driving cyclical dynamics of S&P500 earnings. A common feature of my papers is the application of Bayesian time series techniques to macroeconomic data to pursue new insights on "the impact of oil price shocks on economic activities", "the role of monetary policy in transmitting oil price shocks" in new open economic macroeconomics (NOEM) literature and "intangible capital and corporate earnings" in U.S. business cycle literature.</p> / Thesis / Doctor of Philosophy (PhD)

<P> The three essays in this thesis conduct empirical research on the economics of immigration using data from the Canadian Censuses. In the first paper, I analyze the impact of immigration on native-born Canadians' wage growth by combining an area approach and a skill approach. The estimated effects of immigration from both a first difference regression and a two-stage regression are either statistically insignificant or significantly positive. The results indicate that there is no evidence for a negative impact of the large immigrant influx during the 1990s on the wage growth of natives. The second essay examines the impact of residence in an ethnic enclave on male immigrants' labour force activities. For recent immigrants who arrived in Canada within ten years, the intensity of enclave residence is found to be negatively associated with their labour force participation rate, but positively correlated with their employment probability. However, living in an enclave has no significant effect on the labour force activity of old immigrants whose years-since-migration is more than twenty. These findings are robust to probit and instrumental variable estimations. In the third essay, I examine the returns to education for first, second and third generation immigrant men. Multivariate regression results indicate that the third generation with at least postsecondary education earn more than the equally educated first and second generations. However, the third generation do not have a wage premium over the second generation when they have high school education and lower. I explain the well-educated second generation's difficulty in translating their intellectual ability into productivity by their ethnic and linguistic distance from the Canadian mainstream, and by negative city-specific effects. I then suggest that immigrant assimilation policies that target the well-educated first and second generations should be designed to promote the acceptance of their human capital by the Canadian labour market. </p> / Thesis / Doctor of Philosophy (PhD)

<P> This dissertation aims to advance empirical research in the realm of knowledge sharing in virtual communities and to help practitioners better understand the factors that inhibit (cost) or motivate (benefit) such behaviour. The impact of some costs and benefits (factors derived from social exchange theory) may be contingent upon certain social contexts or conditions (factors derived from social capital theory). To this end, two research models were developed (i.e., a main effects model and an interaction model) that integrate these two theories together. New constructs specific to the virtual community context were also incorporated. To test these models, an online survey was administered to 968 members of a large IT professional virtual community comprising millions of registered users. </p> <p> Findings from a structural equation modeling analysis of this data set suggest that specific benefits and social capital factors have direct effects on an individual's intention to share knowledge, and more importantly, the impacts of some benefits are contingent upon certain social capital factors. Specifically, the impact of online score rewards on an individual's intention to share knowledge with others in the virtual community is contingent upon that person's trust in the people who are seeking knowledge from that individual. Additionally, the impact of reciprocity on an individual's intention to share knowledge is moderated by pro-sharing norms in the virtual community. </p> <p> A major contribution of this dissertation is the provision of new theoretical insights that help explain how certain benefits and social capital factors affect knowledge sharing activity in virtual communities. It is hoped that these insights will help builders and managers of knowledge-based virtual communities better promote online knowledge sharing behaviours and improve the sustainability of such communities in the future. </p> / Thesis / Doctor of Philosophy (PhD)