Assume the model is a closed economy, and the shock is from technology progress. This research, based on a real business cycle model, explores the government¡¦s optimal taxation on consumption and labor income under the condition that representative agent¡¦s utility function has consumption externalities as well as leisure externalities. In the following, by changing the value (namely, by setting the consumption and leisure externalities parameter as either positive or negative), this research examines cyclical property of optimal taxation in terms of four situations occurred. The results indicate that, when labor income taxation in the economy is a constant, consumption externalities parameter is negative, leisure externalities parameter is positive, then the consumption taxation is countercyclical at this time; at other times the consumption taxation is procyclical. On the other hand, suppose consumption taxation is a constant, consumption externalities parameter is negative, leisure externalities parameter is positive, or both consumption and leisure externalities parameter are negative, then labor income taxation is countercyclical at this time; at other times the labor income taxation is procyclical.

Understanding the Equity Risk Premium (ERP) and the factors affecting it is cardinal to financial economics, particularly to equity research analysts, domestic and international institutional investors and financial economist. Since the seminal work of Mehra and Prescott (1985) there has been an exponential rise in the research explaining the reasons for ERP puzzle. This review, systematically, investigates the literature related to ERP in four key dimensions. The first dimension is regarding the issues related to different techniques of estimating the ERP. The second dimension is regarding the studies that explain the reasons of existence of the ERP puzzle by making modifications to the preference structures. The third is regarding the macroeconomic variables that help in predicting ERP and the fourth deals with studies that are conducted in the international context. In addition to this, this review meticulously captures some important limitations of the existing literature regarding the estimation of ERP and identifies the domestic and international determinants of ERP, in particular the UK ERP and proposes novel future directions of research. These future research directions have two important implications for my PhD. The first is the academic contribution that predominantly comes from methodological contribution of estimating the ERP. The second is the practical contribution that comes mainly from identifying the unique set of variables (UK domestic and international), which are of prime importance to the domestic and foreign institutional investors because of the financial crisis of 2008-2009 and which should affect the UK ERP.

This dissertation consists of three essays on monetary economics. The first two essays have a focus on the zero lower bound on the nominal interest rate (ZLB) and the Great Recession. In the first essay, I investigate optimal discretionary monetary policy under the ZLB in the case of a distorted steady state due to monopoly and taxation. I find that the central bank in a more distorted economy would cut the interest rate less aggressively under a particular adverse demand shock. This occurs because the ZLB is less likely to bind and the economy escapes from the ZLB sooner. In addition, I show that the conventional linear-quadratic method is not accurate when the ZLB binds. In the second essay, I model the role of subprime lending, deleveraging and an incomplete financial market in driving an economy to the liquidity trap with binding ZLB. There are two key features that differentiate my work from the current literature of deleveraging and the ZLB. First, I endogenize the debt limit of borrowing-constrained households by tying it to the market value of collateral assets. Second and more importantly, I allow for subprime lending. I am able to show that the second feature drives the economy to the ZLB more likely under an adverse shock to the credit market. When the ZLB binds, a great recession emerges with a free fall in output and the price level, mostly due to the Fisherian debt deflation that puts more debt burden on the borrowers. The third essay examines the role of habit formation in solving the persistence problem - output response is transient and not hump-shaped under a monetary shock - in the conventional state dependent pricing model. Intuitively, incorporating habit formation makes consumers less aggressive in spending under a shock, resulting in more persistent response of output. With a moderate habit formation, I am able to show that the model produces hump-shaped and very persistent response of output under a monetary growth shock.

Sustaining behaviour change is fundamental for the effective uptake of policies and practices aimed at improving individual and collective health, yet it can be very difficult for individuals to adhere to new desired health-related behaviours. A prospective solution is to focus on instilling these behaviours as a habit. Once instilled as a habit, behaviours are performed automatically given specific cues, and they relieve the cognitive stress of having to make a volitional decision towards performing the behaviour - making it more resistant to relapse. Several information systems (IS) are being proposed to help individual users instil target behaviours as habits so that they can be performed even when intentions shift. However, these systems tend to be designed in an ad hoc manner and, as a result, their effectiveness can vary substantially. To better guide the design of information systems that can support users in forming health-related behaviours as a habit, we define a subclass of systems called Habit Formation Support Systems (HFSS) and adopt the design science research approach to develop two artifacts: (1) a design-relevant theory explaining and predicting how IS-supported habit formation can be achieved called the Theory for the Formation of IS-Supported Habits (T-FISSH); and (2) a suite of design principles to guide the design of systems that can effectively support users in forming a desired health-related behaviour as a habit. We contend that habit theory and IS continuance theory can be used to anchor the development of the two artifacts. The T-FISSH was refined and validated using exploratory and confirmatory focus groups with academics and health behaviour change practitioners respectively. The design principles were refined with systems design and development professionals and validated through a reusability check that involved a design activity and reusability questionnaire. The theoretical contribution of the thesis lies in moving the habit formation knowledge base into the design realm through the development of a design-relevant explanatory/predictive theory. From a practical perspective, this research presents a suite of theory-anchored design principles that are intended to guide the design and development of systems that can support users in forming desired health-related behaviours as a habit.

Att upprätthålla regelbundna träningsvanor har visat sig oerhört viktigt för att främja både mental och fysisk hälsa. Denna kvalitativa studie undersöker de motivationsfaktorer som bidrar till att upprätthålla träningsrutiner och hur avsaknaden av dessa kan bidra till upplevt motstånd och därmed begränsa individens strävan om långsiktig fysisk aktivitet. Studien baseras på material från tio intervjuer med personer som har tränat minst två gånger i veckan i ett halvår. Genom tematisk analys framträdde fyra centrala teman: Lyssna på kroppen, Planerat beteende, Återkoppling samt Positiva hälsoeffekter av träning. Dessa teman belyser både främjande och begränsande faktorer vid upprätthållandet av hållbara träningsrutiner samt träningens upplevda hälsofördelar för individen. Resultatet diskuteras utifrån Self-Determination teorin och tidigare forskning kring beteendeförändringar. Det visade hur intern och extern motivation kan komplettera varandra i strävan med att bibehålla varaktiga träningsrutiner. Sammantaget tycks regelstyrt beteende vara en avgörande faktor för att brygga gapet mellan värderingsstyrda och luststyrda träningsvanor.

This collection of essays examines the impact of two antecedents of household food consumption: SNAP and habit formation to nutrients. Household food choice invariably plays a substantial role in health outcomes such as obesity. Low-income households may be especially vulnerable to obesity as they face a more restricted set of food choices due to income constraints and may have less information on healthy eating relative to high-income households. This dissertation unravels this dynamic by providing causal estimates of the effect of two major determinants of food choice. Chapter 2 and chapter 3 test the impact of SNAP participation on consumption of foods that are likely to cause obesity. With some exceptions, SNAP restricts benefits to be spent only on unprepared grocery food items from participating retailers. Chapter 2 considers the broad category of Food Away From Home (FAFH) which is shown to be less healthy than meals prepared at home and shows that SNAP significantly reduces FAFH expenditure of participants. However, the magnitude of this decrease is not large enough to have a tangible impact on obesity. Chapter 3 considers household expenditure on carbonated soda, which is the key source of sugar intake among low-income households. Not only is carbonated soda SNAP-eligible, it is cheaper when purchased with SNAP benefits relative to cash because benefits are exempt from all sales taxes. Results show that SNAP participation leads to a significant rise in carbonated soda sales in low-income counties. I also find that the SNAP tax exemption does not lead to higher consumption among participants relative to non-participants. Chapter 4 tests habit formation to dietary fat using purchases of ground meat and milk products. Products in both categories have salient fat content information on the packaging. Products within each category differ only by fat content and are usually identical otherwise. Differences in habit formation are, therefore, caused by different levels of fat content. Results show a positive association between habit formation and fat content for all products in the ground meat category and all products, except fat-free milk, in the milk category. However, this relationship is modest leading to the conclusion that policy interventions, such as a saturated fat tax, might be effective in discouraging consumption of high fat products.

This dissertation studies a class of path-dependent stochastic control problems with applications to Finance. In particular, we solve the open problem of the continuous time expected utility maximization with addictive consumption habit formation in incomplete markets under two independent scenarios. In the first project, we study the continuous time utility optimization problem with consumption habit formation in general incomplete semimartingale financial markets. Introducing the set of auxiliary state processes and the modified dual space, we embed our original problem into an abstract time-separable utility maximization problem with a shadow random endowment on the product space. We establish existence and uniqueness of the optimal solution using convex duality by defining the primal value function as depending on two variables, i.e., the initial wealth and the initial standard of living. We also provide market independent sufficient conditions both on the stochastic discounting processes of the habit formation process and on the utility function for the well-posedness of our original optimization problem. Under the same assumptions, we can carefully modify the classical proofs in the approach of convex duality analysis when the auxiliary dual process is not necessarily integrable. In the second project, we examine an example of the optimal investment and consumption problem with both habit-formation and partial observations in incomplete markets driven by It\^{o} processes. The individual investor develops addictive consumption habits gradually while only observing the market stock prices but not the instantaneous rates of return, which follow an Ornstein-Uhlenbeck process. Applying the Kalman-Bucy filtering theorem and Dynamic Programming arguments, we solve the associated Hamilton-Jacobi-Bellman(HJB) equation fully explicitly for this path dependent stochastic control problem in the case of power utility preferences. We provide the optimal investment and consumption policy in explicit feedback form using rigorous verification arguments. / text

Submitted by Daniella Santos (daniella.santos@fgv.br) on 2009-08-07T12:32:56Z No. of bitstreams: 1 Dissertação_Jivago_Vasconcelos.pdf: 444244 bytes, checksum: a4ae0c0f31d2c2371cb0e5b822e7da78 (MD5) / Approved for entry into archive by Antoanne Pontes(antoanne.pontes@fgv.br) on 2009-08-07T17:37:15Z (GMT) No. of bitstreams: 1 Dissertação_Jivago_Vasconcelos.pdf: 444244 bytes, checksum: a4ae0c0f31d2c2371cb0e5b822e7da78 (MD5) / Made available in DSpace on 2009-08-07T17:37:15Z (GMT). No. of bitstreams: 1 Dissertação_Jivago_Vasconcelos.pdf: 444244 bytes, checksum: a4ae0c0f31d2c2371cb0e5b822e7da78 (MD5) / Verdelhan (2009) shows that if one is to explain the foreign ex- change forward premium behavior using Campbell and Cochrane (1999) s habit formation model one must specify it in such a way to generate pro-cyclical short term risk free rates. At the calibration procedure, we show that this is only possible in Campbell and Cochrane s framework under implausible parameters speci cations given that the priceconsumption ratio diverges in almost all parameters sets. We, then, adopt Verdelhan s shortcut of xing the sensivity function (st) at its steady state level to attain a nite value for the price-consumption ratio and release it in the simulation stage to ensure pro-cyclical risk free rates. Beyond the potential inconsistencies that such procedure may generate, as suggested by Wachter (2006), with pro-cyclical risk free rates the model generates a downward sloped real yield curve, which is at odds with the data. / Verdelhan (2009) mostra que desejando-se explicar o comporta- mento do prêmio de risco nos mercados de títulos estrangeiros usando- se o modelo de formação externa de hábitos proposto por Campbell e Cochrane (1999) será necessário especificar o retorno livre de risco de equilíbrio de maneira pró-cíclica. Mostramos que esta especificação só é possível sobre parâmetros de calibração implausíveis. Ainda no processo de calibração, para a maioria dos parâmetros razoáveis, a razão preço-consumo diverge. Entretanto, adotando a sugestão proposta por Verdelhan (2009) - de xara função sensibilidade (st) no seu valor de steady-state durante a calibração e liberá-la apenas durante a simulação dos dados para se garantir taxas livre de risco prócíclicas - conseguimos encontrar um valor nito e bem comportado para a razão preço-consumo de equilíbrio e replicar o foward premium anomaly. Desconsiderando possíveis inconsistências deste procedimento, sobre retornos livres de risco pró-cíclicos, conforme sugerido por Wachter (2006), o modelo utilizado gera curvas de yields reais decrescentes na maturidade, independentemente do estado da economia - resultado que se opõe à literatura subjacente e aos dados reais sobre yields.

Research macroeconomists have witnessed remarkable methodological developments in mathematical, statistical, and computational tools during the last two decades. The three essays in this dissertation took advantage of these advances to analyze important macroeconomic issues. The first essay, “ Habit Formation, Adjustments Costs, and International Business Cycle Puzzles” analyzes the extent to which incorporating habit formation and adjustment costs in investment in a one-good two-country general equilibrium model would help overcome some of the international business cycle puzzles. Unlike standard results in the literature, the model generates persistent, cyclical adjustment paths in response to shocks. It also yields positive cross-country correlations in consumption, employment, investment, and output. Cross-country correlations in output are higher than the ones in consumption. This is qualitatively consistent with the stylized facts. These results are particularly striking given the predicted negative correlations in investment, employment, and output that are typically found in the literature. The second essay, “Comparison Utility, Endogenous Time Preference, and Economic Growth,” uses World War II as a natural experiment to analyze the degree to which a model where consumers' preferences exhibit comparison-based utility and endogenous discounting is able to improve upon existing models in mimicking the transitional dynamics of an economy after a shock that destroys part of its capital stock. The model outperforms existing ones in replicating the behavior of the saving rate (both on impact and along the transient paths) after this historical event. This result brings additional support to the endogenous rate of time preference being a crucial element in growth models. The last essay, “Monetary Policy under Fear of Floating: Modeling the Dominican Economy,” presents a small scale macroeconomic model for a country (Dominican Republic) characterized by a strong presence of fear of floating (reluctance to have a flexible exchange rate regime) in the conduct of monetary policy. The dynamic responses of this economy to external shocks that are of interest for monetary policy purposes are analyzed under two alternative interest rate policy rules: One being the standard Taylor rule and another that responds explicitly to deviations of the exchange rate with respect to its long-term trend.

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