Food commodity prices fluctuations have important impacts on poverty and food insecurity across the world. Conventional models have not provided a complete picture of recent price spikes in agricultural commodity markets, while there is an urgent need for appropriate policy responses. Perhaps new approaches are needed in order to better understand international spill-overs, the feedback between the real and the financial sectors and also the link between food and energy prices. In this paper, we present results from a new worldwide dynamic model that provides short and long-run impulse responses of wheat international prices to various real shocks.

Una delle realtà economiche più importanti della Sardegna è la produzione di Pecorino Romano DOP. Il contesto nel quale è nato e si è sviluppato ingloba molte delle precondizioni che favoriscono la nascita di un distretto. Il principale obiettivo di questo studio è verificare se il comparto lattiero caseario della Sardegna, focalizzato nella produzione di Pecorino Romano DOP, può creare un effetto distretto. Ciò potrebbe suggerire l'esistenza dello stesso distretto anche se atipico. Per verificare questa ipotesi, in primo luogo è stata esaminata l'efficienza produttiva delle imprese trasformatrici di Pecorino Romano utilizzando il metodo della Frontiera stocastica di produzione. Successivamente sono state cercate le cause delle differenze. Lo studio mostra che i livelli di efficienza osservati sono quasi interamente attribuibili agli input di produzione utilizzati, in particolare al latte. Risulta chiaro che il sistema delle cooperative funziona e che tali aziende ottengono sistematicamente margini di efficienza migliori rispetto alle non cooperative. Le variabili analizzate non permettono di concludere che esiste un "effetto distretto". / One of the most important economic sardinian realities is the production of Pecorino Romano PDO. The context in which it was born and developed incorporates many of the pre-conditions that may contribute to the existence of a district. The main objective of this study is to determine whether the Sardinian dairy industry, focused on the production of Pecorino Romano PDO, may create a district effect. It might suggest the existence of the same district even if atypical. To test this hypothesis, first it was examined the production efficiency of the processing enterprises of Pecorino Romano using the method of stochastic frontier production. Next, we focused on identifying the causes of any differences. The study shows that the efficiency levels observed are almost entirely attributable to production inputs used, particularly milk. It is abundantly clear that the cooperative system works and that these companies get systematically efficiency margins better than the non-cooperative. The variables analyzed do not allow to conclude that there is a "district effect".

This dissertation comprises four essays on the topic of industrial organization and environmental economics. The first essay investigates the profitability of horizontal mergers of firms with price adjustments. We take a differential game approach and both the open-loop as well as the closed-loop equlibria are considered. In the second essay, using the same approach as the first one, we study the profitability of horizontal merger of firms where the demand function is nonlinear. We take into consideration the open-loop equilibrium. The third essay studies the profitability of exogenous output constraint in a differential game model with price dynamics under the feedback strategies. The fourth essay investigates a second-best trade agreement between two countries when pollution spillovers are asymmetric to examine the strategic behavior of governments in using pollution taxes and tariffs under trade liberalization.

This dissertation comprises four essays on the topic of environmental economics and industrial organization. In the first essay, we develop a two-country world differential game model with a polluting firm in each country to investigate the equilibrium of the game between firms when they decide to trade or not and to see under which conditions social welfare coincides with the market equilibrium. In the second essay, we built a model where firms strategically choose whether to participate in an auction/lottery to attain pollution permits, or instead invest in green R&D, to show that, somewhat counterintuitively, a desirable side effect of the auction is in fact that of fostering environmental R&D in an admissible range of the model parameters. The third essay investigates a second-best trade agreement between two countries when pollution spillovers are asymmetric to examine the strategic behavior of governments in using pollution taxes and tariffs under trade liberalization. The fouth essay studies the profitability of exogenous output constraint in a differential game model with price dynamics under the feedback strategies.

This thesis analysis micro and macro aspect of applied fiscal policy issues. The first chapter investigates the extent to which local budget spending composition reacts to fiscal rules variations. I consider the budget of Italian municipalities and exploit specific changes in the Domestic Stability Pact’s rules, to perform a difference-in-discontinuities analysis. The results show that imposing a cap on the total amount of consumption and investment is not as binding as two caps, one for consumption and a different one for investment. More specifically, consumption is triggered by changes in wages and services spending, while investment relies on infrastructure movements. In addition, there is evidence that when an increase in investment is achieved, there is also a higher budget deficit level. The second chapter intends to analyze the extent to which fiscal policy shocks are able to affect macrovariables during business cycle fluctuations, differentiating among three intervention channels: public taxation, consumption and investment. The econometric methodology implemented is a Panel Vector Autoregressive model with a structural characterization. The results show that fiscal shocks have different multipliers in relation to expansion or contraction periods: output does not react during good times while there are significant effects in bad ones. The third chapter evaluates the effects of fiscal policy announcements by the Italian government on the long-term sovereign bond spread of Italy relative to Germany. After collecting data on relevant fiscal policy announcements, we perform an econometric comparative analysis between the three cabinets that followed one another during the period 2009-2013. The results suggest that only fiscal policy announcements made by members of Monti’s cabinet have been effective in influencing significantly the Italian spread in the expected direction, revealing a remarkable credibility gap between Berlusconi’s and Letta’s governments with respect to Monti’s administration.

This dissertation comprises three essays on the Turkish labor market. The first essay characterizes the distinctive characteristics of the Turkish labor market with the aim of understanding the factors lying behind its long-standing poor performance relative to its European counterparts. The analysis is based on a cross-country comparison among selected European Union countries. Among all the indicators of labor market flexibility, non-wage cost rigidities are regarded as one of the most important factors in slowing down employment creation in Turkey. The second essay focuses on an employment subsidy policy which introduces a reduction in non-wage costs through social security premium incentives granted to women and young men. Exploiting a difference-in-difference-in differences strategy, I evaluate the effectiveness of this policy in creating employment for the target group. The results, net of the recent crisis effect, suggest that the policy accounts for a 1.4% to 1.6% increase in the probability of being hired for women aged 30 to 34 above men of the same age group in the periods shortly after the announcement of the policy. In the third essay of the dissertation, I analyze the labor supply response of married women to their husbands' job losses (AWE). I empirically test the hypothesis of added worker effect for the global economic crisis of 2008 by relying on the Turkey context. Identification is achieved by exploiting the exogenous variation in the output of male-dominated sectors hard-hit by the crisis and the gender-segmentation that characterizes the Turkish labor market. Findings based on the instrumental variable approach suggest that the added worker effect explains up to 64% of the observed increase in female labor force participation in Turkey. The size of the effect depends on how long it takes for wives to adjust their labor supply to their husbands' job losses.

Chapter 1 studies how consumers’ switching costs affect the pricing and profits of firms competing in two-sided markets such as Apple and Google in the smartphone market. When two-sided markets are dynamic – rather than merely static – I show that switching costs lower the first-period price if network externalities are strong, which is in contrast to what has been found in one-sided markets. By contrast, switching costs soften price competition in the initial period if network externalities are weak and consumers are more patient than the platforms. Moreover, an increase in switching costs on one side decreases the first-period price on the other side. Chapter 2 examines firms’ incentives to invest in local and flexible resources when demand is uncertain and correlated. I find that market power of the monopolist providing flexible resources distorts investment incentives, while competition mitigates them. The extent of improvement depends critically on demand correlation and the cost of capacity: under social optimum and monopoly, if the flexible resource is cheap, the relationship between investment and correlation is positive, and if it is costly, the relationship becomes negative; under duopoly, the relationship is positive. The analysis also sheds light on some policy discussions in markets such as cloud computing. Chapter 3 develops a theory of sequential investments in cybersecurity. The regulator can use safety standards and liability rules to increase security. I show that the joint use of an optimal standard and a full liability rule leads to underinvestment ex ante and overinvestment ex post. Instead, switching to a partial liability rule can correct the inefficiencies. This suggests that to improve security, the regulator should encourage not only firms, but also consumers to invest in security.

This dissertation mimics the Turkish college admission procedure. It started with the purpose to reduce the inefficiencies in Turkish market. For this purpose, we propose a mechanism under a new market structure; as we prefer to call, semi-centralization. In chapter 1, we give a brief summary of Matching Theory. We present the first examples in Matching history with the most general papers and mechanisms. In chapter 2, we propose our mechanism. In real life application, that is in Turkish university placements, the mechanism reduces the inefficiencies of the current system. The success of the mechanism depends on the preference profile. It is easy to show that under complete information the mechanism implements the full set of stable matchings for a given profile. In chapter 3, we refine our basic mechanism. The modification on the mechanism has a crucial effect on the results. The new mechanism is, as we call, a middle mechanism. In one of the subdomain, this mechanism coincides with the original basic mechanism. But, in the other partition, it gives the same results with Gale and Shapley's algorithm. In chapter 4, we apply our basic mechanism to well known Roommate Problem. Since the roommate problem is in one-sided game patern, firstly we propose an auxiliary function to convert the game semi centralized two-sided game, because our basic mechanism is designed for this framework. We show that this process is succesful in finding a stable matching in the existence of stability. We also show that our mechanism easily and simply tells us if a profile lacks of stability by using purified orderings. Finally, we show a method to find all the stable matching in the existence of multi stability. The method is simply to run the mechanism for all of the top agents in the social preference.

Can the potential availability of unemployment insurance (UI) affect the behavior of employed workers and the duration of their employment spells? After discussing few straightforward reasons why UI may affect employment duration, I apply a regression kink design (RKD) to address this question using linked employer-employee data from the Brazilian labor market. Exploiting the UI schedule, I find that potential benefit level significantly affects the duration of employment spells. This effect is local to low skilled workers and, surprisingly, indicates that a 1\% increase in unemployment benefits increases job duration by around 0.3\%. Such result is driven by the fact that higher UI decreases the probability of job quits, which are not covered by UI in Brazil. These estimates are robust to permutation tests and a number of falsification tests. I develop a reduced-form welfare formula to assess the economic relevance of this result. Based on that, I show that the positive effect on employment duration implies in a higher optimal benefit level. Moreover, the formula shows that the elasticity of employment duration impacts welfare just with the same weight as the well-known elasticity of unemployment duration to benefit level.

The nexus between the environment and development is often analysed through the sustainable livelihoods framework and within this framework, livelihood diversification has dominated much of the literature on sustainable livelihoods in the late 1990s and early 2000s (see Tacoli, 1998; De Haan, 1999; Ellis, 2005). This literature shows that agriculture is not the only source of livelihood for rural people in developing countries and diversifying into non-farm activities is increasingly adopted as a viable livelihood strategy and growing in its importance. Since then however, diversification seems to have lost favour in both the academic and policy discussions. Recently, with climate change and the recognition of its adverse impacts on livelihoods at the forefront in the developing world, there is a revival of interest and discussion on diversification as one of the main strategies by which rural people can respond to the challenges of climate change. This thesis is an effort to document local ways of responding to the impacts of climate change and how existing policy instruments at macro and meso level mainly social protection schemes contribute to the efforts already undertaken by individual households at micro level. In view of this, the thesis contains four studies which provide theoretical and empirical analysis on non-farm diversification and the role of the Productive Safety Net Programme (PSNP) in climate change adaptation in rural Ethiopia. The first study discusses the perceptions of smallholders’ towards climate variability and change as well as local adaptation strategies based on a case study of two districts in Northern Ethiopia. The study makes use of primary data gathered from focus group discussions and in-depth interviews with farmers and secondary data on key climate variables–rainfall and temperature and compares farmers’ perceptions with climate records. The results show that farmers perceive changes in their local climate and their overall perception matches with the results from rainfall and temperature trend analysis. The study also reveals that the greatest impact of these changes in rainfall and temperature are felt on the subsistence farming, which is already hard-pressed to meet the ever-inextricable challenge of food insecurity. Smallholders are also found to employ farm-level adaptation strategies combined with diversification. However, the current level of diversification appears to be dominated by natural resource-based strategies that may not be sufficient to deal with the impacts of current climate variability and expected changes. The second study uses the Ethiopian Rural Household Survey (ERHS) over the period 1994–2009 to analyse the factors that determine participation and returns from non-farm activities in rural Ethiopia. This study uses both the number of activities and income to measure non-farm diversification and estimates a range of micro econometric models. The results suggest that many of the variables that determine non-farm diversification belong to pull factors and are therefore a reflection of accumulation strategies. Despite this dominant pattern, however, it is likely that the poor are also diversifying into non-farm activities to earn income during agricultural off-seasons to smooth consumption. The third study examines the impact of non-farm income diversification on income distribution and poverty using Gini–coefficient decomposition, fixed effects and probit models. These analyses reveal that non-farm income diversification has a positive impact on rural households’ welfare and income distribution. This result strengthens the argument that non-farm income diversification can be a good strategy to lessen agricultural risks. The fourth study uses a sub-sample of the ERHS for the period 2004 and 2009 to examine the impact of the Productive Safety Net Programme (PSNP) as the main social protection scheme on household non-farm income diversification as an adaptation strategy to climate change. This is an impact evaluation study that employs the Difference-in-Differences approach combined with Propensity Score Matching for a panel of 1306 rural households. The results indicate that receiving transfers from the PSNP, on average increases income from non-farm activities and confirms the hypothesis that social protection can promote positive adaptation strategies and serve as effective means of reducing the vulnerability of smallholders to climate change induced shocks.