A) OBJECTIVES AND HYPOTHESES:The main purpose of this PhD thesis is analysing the behaviour of different factors that contribute to increase total factor productivity (TFP) in the context of Spanish manufacturing firms: mainly innovation, formal education and training. The general underlying hypothesis is that small and large firms take different strategic decisions in relation to their investment in these factors and they may obtain different productivity.Departing from the general hypothesis that small and large firms play different roles in our economics, obtain different economic results and take different decisions, the first question analysed in this thesis is that large firms may achieve higher productivity levels for two reasons: first, because they innovate more and employ more qualified employees than small firms, and second, because they may be able to obtain higher returns from this effort. The emphasis placed on the analysis of the effect of returns in explaining the productivity differentials between small and large firms is one of the main contributions of this study.As commented above, human capital is generally considered to have a direct positive effect on productivity. Firms can incorporate more human capital by hiring educated workers, but they can also provide training as a way to increase the skills of their employees. Concretely, training permits adapting workers' skills to the permanent evolution of job requirements and enhances the competitive position of workers and their employers. The main purpose of continuous training is to provide knowledge and adequate skills to occupied employees so that they could adapt to the changing requirements of firms at any moment. Thus, firms' may be interested in providing training to their workers as a way of increasing their productivity.A general finding is that large firms usually provide more training, while small firms face more difficulties in providing training. This can be seen as an additional limitation for small firms to achieve higher productivity levels. The literature suggests different reasons why large firms provide more training: scale economies, training as a way to reduce monitoring costs, access to cheaper capital or higher pay-offs from their investments, among others. According with the reasoning in the previous paragraphs that firm size is a source of heterogeneity, we depart from the idea that small and large firms behave differently in relation to their strategic decisions. We argue that this behaviour involves firms' decisions on training provision as well as other decisions that may determine such provision of training. Thus, we argue that large firms provide more training because they have certain characteristics that allow them to dedicate more efforts to training workers or that require more training. For example, large firms usually have a more qualified labour force and less temporary workers, which permit obtaining higher returns from their investment in training. Also, large firms innovate more and use more advanced technologies or operate in more competitive markets, which requires additional skills of their employees that can not be found in the labour market. These characteristics are considered relevant determinants of training by different studies in the literature. Thus, we argue that small and large firms may differ in these characteristics, which could explain in part that large firms decide to provide more training.Spanish workers receive less training than in other countries and the Spanish firms are smaller than in other economies. Thus, if small firms provide less training, the difficulties of workers in small firms in accessing training can be considered as a limitation for the economy as a whole. The second question we analyse in this thesis is the relative contribution of training determinants in explaining the gap between small and large firms in their decisions to provide training.In addition to the firm characteristics that determine training, those firms that receive subsidies are also expected to provide more training. Actually, there is a system of subsidies in Spain which intends to stimulate firms' provision of training. In this system, firms or groups of firms can obtain public aid to partially finance their training actions so that they make a more intense effort in training their employees. During 2001 and 2002, the eligibility conditions for a subsidy were considerably open to most firms, although the decision on whether to award the subsidy and the amount of it depended upon the evaluation of different authorities and was unknown by the firm until training actions finished.As an extension of the second question in the thesis, we analyse the impact of subsidies on training. Following the firm-size perspective in the previous questions, we deepen in the analysis of the impact of subsidies in small and large firms. Actually, the subsidies regulation gives special importance to stimulating the provision of training in small firms.Finally, we would like to clarify that this thesis started as an analysis of the impact of innovation and educative human capital on productivity. However, the later interest in questions related to human capital and the availability of data on training at firm level, led to the analysis of this component of human capital that is generated within the firm. Given that data on training was only available for some years, we decided not to include it as a determinant of productivity in Part II.B) METHODOLOGYTo address the objectives in the thesis we follow an empirical approach based on a substantive theoretical framework, appropriate quantitative techniques and a comprehensive dataset.In the case of TFP differences across firm size, previous to analysing such differences, we need to measure TFP at the firm level. More concretely, we are interested in a measure of TFP, which summarizes information about the relationship between output and the main inputs involved in the production process (labour, physical capital and materials). The large quantity of theoretical papers that suggest alternative ways of measuring productivity indicates that it is far from easy to suggest a unique measure of productivity. Thus, we compare the most usual TFP indices in the literature on the basis of some a priori-defined mathematical properties and on the basis of the production functions from which they are derived. According with these criteria, we select a TFP index and use it to measure TFP for a sample of Spanish manufacturing firms over the period 1990-2002.Departing from this measure of TFP, we perform a preliminary descriptive analysis on the relationship between productivity, firm size, innovation and education and training. This analysis intends to characterize the evolution of TFP and our variables of interest for the Spanish manufacturing firms in the period of analysis. Particularly, we investigate the growth pace of productivity for small and large firms, paying special attention to the evolution of the differences in TFP between firms of different size classes. Moreover, we study whether the TFP gap by firm size is homogeneous along the distribution and whether the evolution of this gap differs for firms at different points of the distribution. Furthermore, we also analyse whether small and large firms follow different patterns in the intensity of use of technological and human capital. Finally, we provide preliminary evidence on the relationship between productivity, innovative activity, human capital and firm size. This descriptive provides further insights in the relationship between these variables, and constitutes the basis for the analysis of the differences in TFP between small and large firms.The TFP differential between small and large firms is evaluated in the mean of the distribution using the Oaxaca-Blinder decomposition. This methodology permits decomposing the TFP differential and obtain the individual contribution of innovation and human capital in determining TFP. The decomposition departs from an auxiliary regression for each of the two groups under comparison. Every variable determining TFP may contribute to explain the TFP differential in two ways: as differences in characteristics, which means that the differences in TFP are due to the fact that one group invests more in technological or human capital, or as differences in returns, which means that the differences in TFP are due to the fact that one group obtains higher returns from these investments. One of the main contributions of this analysis is using the Oaxaca-Blinder decomposition in the field of empirical industrial organization, and concretely, in analysing the TFP differences between small and large firms.The Oaxaca-Blinder decomposition permits evaluating the TFP differential in the mean of the distribution. However, in the presence of high heterogeneity among firms, the results for the whole distribution may differ from those at the mean of the distribution. Departing from the idea of the Oaxaca-Blinder methodology, we perform a counterfactual distribution analysis. The idea behind the counterfactual distribution analysis is transferring the Oaxaca-Blinder decomposition to the whole distribution, in the sense that we try to separate differences in firms' characteristics and returns at any point of the distribution. The counterfactual distribution analysis compares the density function of the estimated TFP of small firms with the counterfactual (or hypothetical) TFP, obtained by evaluating small firms under the returns of large firms. Thus, the difference between these density functions can be attributed to differences in returns between small and large firms. All in all, this methodology permits assessing the contribution of returns of a given variable at any point of the TFP distribution, which permits identifying the non-homogeneous behaviour of certain groups of firms. As for the analysis of the second question raised in the thesis, the determinants of training, we consider that firms' decision on the provision of training is a double decision process, in which firms first decide whether to provide training or not and then, the quantity of it. Moreover, we argue that in the presence of fixed costs, some potential training providers may not decide to provide training and possible sample selection effects may appear. Thus, we propose estimating firms' decisions on training as a two part model and discuss the possible sample selection problems. On the basis of these estimations, we analyse the effect of the determinants of training on firms' provision decisions: first, we estimate our specification for the subsample of small and large firms and use the results to further analyse the differences in the provision of training by firm size using the Oaxaca-Blinder decomposition; second, on the basis of this specification, we introduce a variable on subsidies on training.As in the case of the TFP differential, we decompose the training provision differential between small and large firms in the mean of the distribution. In this case, we decompose the differential between small and large firms in the probability of providing training and the differential in the quantity of training per worker. The main objective of the Oaxaca-Blinder decomposition in this case is analysing which are the main variables that contribute to explain the gap in the provision of training between small and large firms. Both differences in characteristics and differences in the impact of these characteristics on training may contribute to explain the training gap. The data used in this thesis are mainly drawn from the "Encuesta sobre Estrategias Empresariales" (Survey on Business Strategies, ESEE), an unbalanced panel which covers the period 1990-2002. This survey has been used in many papers on empirical industrial organization for Spain. The reference population of the ESEE is firms with 10 or more employees in the Spanish manufacturing sector. Small firms are defined as those with 10 to 200 employees and large firms, as those with more than 200. Since 1990, an average sample of 1800 firms has been surveyed yearly, on the basis of a questionnaire with more than 100 questions. According to data drawn from the Observatory of European SMEs, firms with 10 or more employees represent 5.3% of the firms in the total Spanish economy in 2000. Although this percentage is low, these firms employ 53% of the workers and produce 80% of the added value. According with data drawn from the DIRCE,3 firms with 10 or more employees represent 18% of the firms in the Spanish manufacturing sector in 2001, indicating that the manufacturing sector concentrates larger firms than other sectors.As for the preliminary descriptive of TFP, we obtain results for a sample of more than 13000 observations over the period 1990-2002, which means that we have around 800-1000 observations per year for more than 2000 different firms. Due to some methodological and econometric requirements, the analysis of the differences in TFP between small and large firms is based on three waves of the survey: 1994, 1998 and 2002. For the each period we count on more than 800 observations per year. Finally, the analysis on the determinants of training, firm size and subsidies is based on data for the last two years of the survey, when data on training were available. In this case, we obtain results based on data for more than 1500 firms per year. In addition, to measure the effect of subsidies on training provision, we use data from other sources.Particularly, data on subsidized training are provided by the Tripartite Foundation for Employment Training and data on the number of workers and worked hours are drawn from General Treasury of the Social Security and the Ministry of Labour and Social Affaires. It should also be mentioned that the software used to obtain the empirical results in the thesis is Gauss v.6.0 and Stata v.9.0, specifieally the commands: "heckman" and "xtprobit" and "xtreg", in the panel data module.C) STRUCTURE OF THE THESISAs previously mentioned, this PhD thesis is structured in three main Parts, each one containing two Chapters that share a common empirical framework or perspective. Due to this structure, an important effort has been done so as not to repeat information and specifying where it is possible to find it. Part I of the thesis includes Chapters 1 and 2. Chapter I presents the different methods that permit measuring productivity and, focusing on the method of index numbers, it reviews the main suggestions in the literature. Different index numbers are compared on the basis of the production functions from which they are derived and on the basis of some a priori-defined mathematical properties or axioms. Next, an index that incorporates desirable properties is chosen to develop the remainder of the analysis in Parts I and II. Chapter 2 presents the ESEE and the particularities of the variables involved in the measurement of TFP, as well as those of firm size, the innovative activity and human capital. Next, it offers a descriptive analysis of the evolution of TFP, as well as a descriptive of TFP in relation with the main variables of interest.Part II of the thesis comprises Chapters 3 and 4 and it investigates the differences in TFP between small and large firms. Chapter 3 starts with a review of theoretical and empirical literature that relates firms' productivity, size and innovation and human capital, in their role of TFP determinants. Next, we explain the empirical specification and the methodology of estimation. This Chapter contains also a descriptive analysis and the results of the estimation. Finally, the size TFP-gap is evaluated in the mean of the TFP distribution using the Oaxaca-Blinder decomposition. Chapter 4 departs from the framework, specification and results in the previous Chapter and evaluates the TFP gap between small and large firms along the distribution using the counterfactual distribution analysis.The last Part of the thesis contains Chapters 5 and 6 and it studies two different questions related with firms' determinants of training. Chapter 5 analyses the differences between small and large firms in their training provision decisions. This Chapter starts with a revision of the literature on the relationship between firm size and training and determinants of training. This Chapter also discusses the empirical specification and some methodological issues related with its estimation. Next, it provides a descriptive analysis and the results of the estimation. Finally, it explains the decomposition of training decisions using the Oaxaca-Blinder methodology and its results. Chapter 6 departs from the theoretical framework in the Chapter 5 and analyses the impact of subsidies on firms' provision decisions. First it describes the system of subsidies in Spain and the theoretical approach. Then, it describes the data used to measure subsidies. On the basis of the empirical model and specification in the previous Chapter, it provides the results for the estimation the effect of subsidies on training. Such effects are analysed for the total sample, as well as for the small and large firms' subsamples.

La intensificació agrícola que s'ha produït al llarg de les darreres dècades ha fet possible un augment de la producció. Aquesta intensificació, però, ha ocasionat greus conseqüències pel medi, entre les que destaca, la pèrdua de biodiversitat. La pèrdua de diversitat d'espècies arvenses és un dels problemes més rellevants perquè tenen un paper clau en el funcionament dels sistemes agrícoles. La intensificació agrícola s’ha produït a diferents escales espacials. A escala de paisatge, l’agregació de parcel•les i la reducció dels hàbitats associats als conreus a causa de la concentració parcel•lària ha comportat una important simplificació del paisatge agrícola. A escala local, la intensificació agrícola s’ha posat de manifest amb el monocultiu, la llaurada intensiva, la fertilització química i l’aplicació d’herbicides. En aquesta tesi s'ha integrat aquests dos aspectes de la intensificació agrícola mitjançant diferents aproximacions, amb l’objectiu d’aprofundir en el coneixement dels seus efectes sobre la diversitat de la flora arvense dels conreus de cereals de secà. Amb aquesta finalitat, es van seleccionar 18 localitats de la Catalunya Central situades en un gradient de complexitat del paisatge i, en cadascuna d'elles, una finca cerealista amb gestió ecològica i una amb gestió convencional. Els resultats d’aquesta tesi doctoral mostren que la intensificació de les pràctiques agrícoles, avaluada per mitjà de (i) la comparació entre parcel•les amb gestió ecològica i convencional (Capítols 1, 3 i 4), (ii) diverses variables relacionades amb la gestió com ara les aportacions de nitrogen amb la fertilització (Capítols 2 i 3) i (iii) la seva integració en un índex d’intensificació agrícola (Capítol 2), afecta negativament la riquesa de la flora arvense. A més, la intensificació agrícola comporta la reducció de la riquesa de grups funcionals com les lleguminoses i la pèrdua d’espècies segetals poc freqüents i abundants (Capítol 1). La caracterització de les pràctiques agrícoles de cada una de les parcel•les estudiades ha permès constatar que la gestió ecològica és, en general, menys intensa que la gestió convencional (Capítol 2), però a més, ha permès conèixer que existeix una gran heterogeneïtat en la intensitat de la gestió en cada sistema. Això indica que no es pot associar sempre la gestió ecològica amb pràctiques agrícoles poc intenses, i la gestió convencional amb pràctiques agrícoles molt intenses. Els resultats també mostren que la riquesa d’espècies arvenses dels camps ecològics i convencionals no varia en relació a les característiques del paisatge que els envolta (Capítol 3). L’efecte de la complexitat del paisatge sobre la riquesa de la flora arvense és un tema de debat perquè s’han obtingut resultats contraposats. La majoria d’estudis que constaten un efecte positiu de la complexitat del paisatge sobre la riquesa d'espècies analitzen la flora arvense dels marges dels camps i/o de les vores (la part externa del camp adjacent al marge). Aquesta tesi constata que no es produeix aquest efecte als centres dels camps, bé per la limitada dispersió de les llavors o bé per la intensitat més gran de les pràctiques agrícoles als centres que als marges dels camps. Una de les conseqüències de la intensificació agrícola és l’increment de l’abundància d’algunes espècies arvenses, com ara el margall (Lolium rigidum) o la cugula (Avena sterilis). L’elevada dominància d’aquestes espècies fa que es puguin considerar espècies invasores dels conreus cerealístics. Els resultats d’aquesta tesi (Capítol 4) mostren que l’augment d’aquestes espècies invasores nadiues afecta negativament l’abundància i la riquesa d’espècies de la comunitat arvense resident, tal i com s’ha descrit per algunes espècies exòtiques. / Agricultural intensification over the past decades, at both the local (management intensification) and the landscape scale, is the main reason for the current biodiversity decline. The decline of arable weed diversity in agro-ecosystems is a matter of great concern because of its key role in supporting biodiversity at higher trophic levels. This thesis focus on the biotic and abiotic factors that may have an influence on arable weed species, in order to evaluate their effect and develop mechanisms to counteract the increasing loss of weed diversity. To fulfil these objectives, several experiments were performed in central Catalonia, in 18 localities placed along a gradient of landscape complexity. In each locality, an organic and a conventional cereal farm were selected. The results of this thesis show that intensification of management, evaluated by means of (i) the comparison of organic and conventional fields (Chapters 1, 3 and 4), (ii) several management variables (Chapters 2 and 3) and an index of land-use (Chapter 2), negatively affects weed flora. The characterization of farming practices (Chapter 2) indicates that land-use intensity is lower in organic fields but also that there is a gradient of land-use intensity between and within organic and conventional farms. These results suggest that it is an over-simplification to always equate organic farming with low intensive management. This thesis also demonstrates that landscape complexity does not influence weed flora within cereal fields (Chapter 3), although several authors have reported some effects on boundaries and crop edges. Finally, the results also highlight that native invaders, such as Lolium rigidum and Avena sterilis, could have negative effects on diversity of weed communities, as it has been previously proved for alien species (Chapter 4).

Even though unhealthy habits, drinking, smoking and overeating, are among the most expensive burdens for the health system, much research is still needed to understand how individuals form them, how do they correlate between them and what impacts do they have in labor productivity. The first paper in this thesis fills in the gap of un- derstanding whether individuals substitute among habits by exploring the effect that quitting smoking has on obesity. The second paper analyze the impact that the business cycle, that is, unemployment rate and income per capita have on drinking participation and alcohol consumption. To overcome the lack of a true longitudinal panel which would prevent us from obtaining unbiased estimates in these two first papers, we use cohort analysis methodology to control for unobservables, while instrumenting the habit deci- sion and introducing dynamics into the estimation equation. The third paper focuses on the effects of smoking over labor productivity. Here we exploit many outcomes that are potentially correlated with individual labor productivity using a longitudinal panel and instrumenting the smoking decision. The three papers make use of a dataset on US regulations regarding tobacco use, which was self developed from the compilation of the different laws enacted by the states. / Tot i que els hàbits no saludables, com poden ser beure, fumar o menjar en excés, són algunes de les càrregues més cares per al sistema de salut, encara és necessari molt més recerca per entendre com els individus formen els hàbits, com aquestes es correlacionen entre si, i quins efectes tenen per a la productivitat. El primer document busca comprendre si els individus substitueixen uns hàbits per altres, en particular, analitza l'impacte que deixar de fumar té sobre l'obesitat. El segon article analitza l'impacte que té el cicle econòmic, és a dir, la taxa d'atur i l'ingrés per càpita, sobre la decisió de beure i sobre el volum d'alcohol consumit. Per superar la manca d'un veritable panell longitudinal que impedeix obtenir estimacions no esbiaixades, en aquests dos primers articles s'ha utilitzat la metodologia de l'anàlisi de cohortes per a poder controlar d'aquesta manera per a les característiques no observables, en particular les preferencies, al mateix temps que s'ha instrumentat la decisió de l'hàbit i s'ha introduït dinàmica en l'equació d'estimació. El tercer document se centra en els efectes del tabaquisme sobre la productivitat laboral. Aquí s'exploren moltes variables que potencialment estan correlacionades amb la productivitat del treball, utilitzant un panell longitudinal i instrumentant la decisió de fumar. Els tres documents fan servir un conjunt de dades sobre reglaments pel que fa a l'ús del tabac als Estats Units.

Los estudios sobre crecimiento económico han considerado desde antiguo el papel del progreso técnico exógeno en la función de producción agregada (Solow, 1957) como una de las dimensiones de mejora de la eficiencia. La investigación posterior, sin embargo, ha buscado la forma de asociar las ganancias de productividad con factores más específicos que el simple transcurso del tiempo creando el cuerpo de las teorías del crecimiento endógeno. Así, tanto en la teoría como en las aplicaciones se han sucedido los análisis sobre la importancia de las generaciones de capital y la cualificación del trabajo como determinantes del crecimiento de la producción en general y de las ganancias de productividad del sector privado, en concreto. Se dejaba, no obstante, una puerta abierta a otras posibles explicaciones. No fue hasta finales de los ochenta cuando surgió entre los economistas el interés por analizar el impacto del capital público como otro posible determinante del crecimiento económico, a fin de encontrar explicaciones a la caída del crecimiento de productividad que estaba teniendo lugar en aquellos momentos en los países desarrollados. Sin embargo, ¿por qué entre las variables que concentraron la atención de los economistas para explicar este fenómeno se encontraba el capital público? Esta cuestión y otras más han sido analizadas a través de una extensa literatura, tanto teórica como empírica, y en el caso concreto del efecto de las infraestructuras en el desarrollo económico tampoco han faltado los análisis, y la presente tesis doctoral quiere incidir en este punto, aunque es preciso remarcar que nuestro estudio se va a concentrar en el ámbito regional. El estudio de las economías regionales es un ámbito que ha ganado últimamente importancia en nuestro país a consecuencia de la transformación de España en un Estado formado por Comunidades Autónomas y de su ingreso en la Comunidad Europea. Eso ha llevado a potenciar el estudio de las externalidades como factores determinantes del crecimiento económico. De esta forma, la presente tesis intenta no trasladar automáticamente conceptos macroeconómicos, sino que procura otorgar una especial importancia al papel de la geografía y del espacio, y considerar de una manera explícita las externalidades, "spillovers" o vínculos regionales. Teniendo en cuenta estas motivaciones genéricas, los objetivos de la presente tesis son tres: 1) Realizar una revisión crítica de la literatura existente en torno al análisis de los efectos de las infraestructuras en el desarrollo económico regional; 2) Abordar teórica y empíricamente el efecto de las infraestructuras en el desarrollo económico, y 3) Desarrollar un marco teórico que vaya más allá de las funciones de producción, que nos permita entender el proceso de influencia de las infraestructuras. Para poder tratar estos objetivos, el trabajo se estructura internamente en tres partes claramente diferenciadas. En la primera se recogen las ideas teóricas que han marcado de una manera más directa la elaboración de esta tesis. En la segunda se sigue la línea más tradicional en el estudio de las infraestructuras, analizando concretamente el posible efecto diferencial de las infraestructuras según el nivel de desarrollo de la economía. En la tercera parte se utiliza el marco teórico de la teoría de la dualidad para cuantificar y desmenuzar el efecto de las infraestructuras en el comportamiento de las empresas, permitiendo un mejor entendimiento del vínculo entre los "inputs" públicos y la naturaleza del proceso de producción. Un capítulo de conclusiones y un apartado de bibliografía completan el contenido de esta tesis. / The present dissertation focuses on infrastructure effect on economic growth. However, since public impact is analysed as a regional level, the automatic translation of macroeconomic topics is avoided, stressing the role of geography and space through the explicit consideration of externalities across regions. Specifically, the goal of the dissertation is threefold. First, a literature review both on infrastructure effects and cross-regions externalities is made. Also, given the regional scope of the dissertation, we claim the geography has scarcely been considered in empirical regional studies, which have mostly forgotten the possibility of externalities as a growth transmission tool. We suggest the use of Spatial Econometrics as the most accurate framework to test their presence. Second, we consider infrastructure effect both as a theoretical and empirical level. Instead of focusing on the specific elasticity of output with respect to public capital, the conditions that make the relationship between infrastructure and regional growth so complex is analysed. First, the use of the variable expansion method reveals both the absence of a direct effect of infrastructure and the fact that the link between infrastructure and growth depends on the level of the existing stock (threshold level). Second, we examine the importance of the spatial dimension in infrastructure impact, due to spillover effects. In this sense, the dissertation provides evidence of the existence of spatial autocorrelation processes in the considered model. Finally, we find out that industry is the sector which reaps the most benefits from an increase in the infrastructural dotation whereas the results are very sensitive to the presence of sectorial spillovers. As a third goal, the cost reductions associated with infrastructure provision are examined through the application of the duality theory. This theoretical framework allows us to determine a wide range of public capital effects both in the short and long term. By considering the impact of infrastructure on private investment decision, which we call the infrastructure's location effect, it is observed how, besides the direct effect on costs in the short run, infrastructure presents an indirect channel of influence through its effect on private capital.