A thesis submitted to the Faculty of Commerce, Law and Management, University of the Witwatersrand, Johannesburg, in Ful llment of the Requirements for the Degree of Doctor of Philosophy in Economics 15 July, 2015 / The thesis focuses on the sources of macroeconomic uctuations in ten (10) selected African economies over the period 1990-2011. Data for the study were obtained from the International Financial statistics (IFS), the World Bank, and Central Bank database of the selected countries. We formulate a dynamic stochastic general equilibrium (DSGE) model for the thesis. We estimate the model using quarterly time series data. Due to data availability, the sample size di¤ers from one country to the other. First, we investigate the relative contributions of internal and external shocks to economic uc- tuations in African economies. Second, we evaluate the signi cance of the balance sheet channel in African economies. Third, we investigate the ef- fectiveness of sovereign wealth funds in reducing macroeconomic volatility caused by commodity price shocks. The thesis has 5 chapters. Chapter 1 is the general introduction. Chapters 2, 3, and 4 are stand-alone related papers on macroeconomic uctuations. Chapter 5 is the conclusion. Chapter 1 introduces the study. We discuss the research problem, the moti- vation, the objectives, and the research questions. We also explain both our theoretical and empirical contributions to the literature. Moreover, we high- light the signi cance and the key ndings of the study. Finally, we conclude the chapter with a brief outline on the organisation of the study. Chapter 2 investigates the relative contributions of internal and external shocks to macroeconomic uctuations in African economies. We formulate and estimate a monetary DSGE model to examine the sources of economic uctuations in ten African countries. The model is estimated with the Bayesian technique using twelve macroeconomic variables. Generally, the ndings indicate that both the internal and external shocks signi cantly in- uence output uctuations in African countries. Over a four quarter horizon, internal shocks are dominant while over eight to sixteen quarter horizons, the external shocks are dominant. Among the external shocks, external debt, ex- change rate, foreign interest rate and commodity price shocks account for a large part of output variations in African economies. Money supply and productivity shocks are the most important internal shocks contributing to output uctuations in African countries. To ensure macroeconomic stability, African countries need to formulate appropriate exchange rate and exter- nal debt management policies, diversify the economies, and create sovereign wealth funds (SWFs) or use hedging instruments. Chapter 3 evaluates the quantitative signi cance of the balance sheet chan- nel in African economies. We construct an open economy monetary DSGE model where entrepreneurs nance investment by issuing foreign currency- denominated debt. The model is estimated with Bayesian technique. The evidence suggests that the balance sheet e¤ects are empirically important in African economies. The marginal likelihood results clearly favour the model with nancial frictions. Moreover, the ndings indicate that the balance sheet e¤ect reduces the e¤ectiveness of monetary policy, raises the sensitiv- ity of the risk premium to external debt, and contracts output. This indi- cates that exchange rate depreciation is contractionary in African economies. We conclude that African countries should reduce their exposure to foreign currency-denominated debt and also deepen their domestic bond markets. Chapter 4 investigates the e¤ectiveness of sovereign wealth funds (SWFs) in reducing macroeconomic volatility in commodity exporting African countries. We formulate and simulate a dynamic stochastic general equilibrium (DSGE) model that features SWFs. The simulation results suggest that the creation of SWFs can reduce macroeconomic volatility in commodity exporting coun- tries. Particularly, SWFs can reduce government expenditure, real exchange rate, and external debt volatility. Since these are the channels through which commodity price shocks are transmitted to the African economies, we rec- ommend that African countries should create SWFs to sterilize the in ow of commodity revenue and to prevent the resource curse problem. Chapter 5 concludes the study. We summarize the key ndings in Chapters 2, 3, and 4. We highlight the policy implications of our ndings. Finally, we suggest areas for further research.

Thesis advisor: Peter Gottschalk / Thesis advisor: Shannon Seitz / This dissertation contains two essays in labor economics. It provides a descriptive analysis on income volatility and develops a microeconomic model to study how married couples make joint decisions in response to such income volatility. The first essay examines the recent trends in household income volatility in the United States, West Germany and Great Britain, and compares household income volatility with individual income volatility. I estimate a formal error components model using the Cross-national Equivalence File from 1979 to 2004. I find that household income volatility, measured by the transitory variance of household income, accounts for more than half of the total income variance for all three countries. Despite the differences in the total household income variances among the three countries, the permanent variances converges since the late 1990s. The household earnings volatility is always lower than the individual earnings volatility for married couples, which suggests some evidence of intra-household insurance. In the second essay I examine whether married couples make joint labor supply decisions in response to each other's wage shocks. The study of this question aids in understanding the link between the recent rise in earnings volatility and household joint decisions. I develop an intra-household insurance model based on the collective framework, which allows for insurance against both permanent and transitory wage shocks from both partners. Estimation using Survey of Income and Program Participation shows that individuals increase labor supply in response to spouse's adverse wage shocks and such labor supply responses are larger when shocks are permanent than transitory. A household makes less transfer to the individual with more volatile income, which can be considered as a price for insurance.This intra-household insurance reduces earnings volatility by about 1.2% to 7.7%. These results suggest that joint labor supply decisions provide a smoothing effect on shocks to earnings and household income. / Thesis (PhD) — Boston College, 2009. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Economics.

Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro / Uma forma de generalizar a teoria de Einstein da gravitação é incorporar na lagrangiana termos que dependem de escalares formados com os tensores de Ricci e Riemann, tais como (Ricci)2, ou (Riemann)2. Estas teorias tem sido estudadas intensamente nos últimos anos, já que elas podem ser usadas para descrever a expansão acelerada do universo no modelo cosmológico standard. Entre os desfios de modificar a teoria de Einstein, se encontra o de limitar a ambiguidade na escolha da dependência da lagrangiana com os escalares antes mencionados. A proposta desta dissertação é a de colocar limites sobre as possíveis lagrangianas impondo que as ondas (isto é, perturbações lineares) se propaguem no vácuo sem que apareça, shocks. / One way to generalize Einstein's theory of gravitation is by the addition of terms that depend on scalar formed with Ricci and Riemann tensors, such as (Ricci)2 or (Riemann)2 in the lagrangians.These theories have been intensively studied in recent years, since they can be used to describe the accelerated expansion of the universe in the standard cosmological model. One of the challenges to modify Einstein's theory is to limit the ambiguity in the choice of the dependence of the Lagrangian with the aforementioned scalars. The purpose of this dissertation is to put limits on the possible Lagrangians imposing that the waves(ie, linear perturbations) propagate in a vacuum without the appearance of shocks.

In this paper we analyse the influence of sector specific developments in productivity and demand on net entry and employment in 19 industrial sectors of the Austrian economy. Based on the model of structural dynamics of Pasinetti, we develop an identification scheme that allows us to extract technology and demand shocks, by means of a structural vector autoregressive (SVAR) model with long-run restrictions. We study the patterns of productivity and demand shocks across industries by means of a principal components analysis and find that sectoral and macro-economic developments in demand strongly correlate, while this is not the case for technology shocks. Impulse-response analysis shows that for almost all sectors productivity growth rates experience an immediate increase to positive technology shocks while the hours worked decline as conjectured by Pasinetti. Finally, we use the identified shocks as explanatory variables in time-series cross-section regressions on net-entry and employment data. Both types of shocks are able to explain dynamics on the industry level in terms of employment and sales but not firm dynamics. (author's abstract) / Series: Working Papers Series "Growth and Employment in Europe: Sustainability and Competitiveness"

Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro / Uma forma de generalizar a teoria de Einstein da gravitação é incorporar na lagrangiana termos que dependem de escalares formados com os tensores de Ricci e Riemann, tais como (Ricci)2, ou (Riemann)2. Estas teorias tem sido estudadas intensamente nos últimos anos, já que elas podem ser usadas para descrever a expansão acelerada do universo no modelo cosmológico standard. Entre os desfios de modificar a teoria de Einstein, se encontra o de limitar a ambiguidade na escolha da dependência da lagrangiana com os escalares antes mencionados. A proposta desta dissertação é a de colocar limites sobre as possíveis lagrangianas impondo que as ondas (isto é, perturbações lineares) se propaguem no vácuo sem que apareça, shocks. / One way to generalize Einstein's theory of gravitation is by the addition of terms that depend on scalar formed with Ricci and Riemann tensors, such as (Ricci)2 or (Riemann)2 in the lagrangians.These theories have been intensively studied in recent years, since they can be used to describe the accelerated expansion of the universe in the standard cosmological model. One of the challenges to modify Einstein's theory is to limit the ambiguity in the choice of the dependence of the Lagrangian with the aforementioned scalars. The purpose of this dissertation is to put limits on the possible Lagrangians imposing that the waves(ie, linear perturbations) propagate in a vacuum without the appearance of shocks.

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Doctor of Philosophy / Department of Economics / Lance Bachmeier / In the first chapter I study the effects of oil price shocks on economic activity at the U.S. state-level, an innovative feature of this dissertation. States which rely more heavily on manufacturing or tourism are more adversely affected by adverse oil price shocks, while states which are major energy producers either benefit or experience insignificant economic changes from historically large oil price increases. Additionally, oil price increases from 1986 to 2011 have not impacted state-level economies to the same degree as increases from 1976 to 1985. This discrepancy can be attributed to a fundamental change in the structure of the U.S. economy, for example, a declining manufacturing sector or an increase in the efficiency with which energy is used in the production process. In the second chapter I explore the effects of alternative measures of energy price shocks on economic activity and examine the relative performance of these alternative measures in forecasting macroeconomic activity. The alternative energy prices I consider are: gasoline, diesel, natural gas, heating oil and electricity. I find that alternative measures of energy price shocks produce different patterns of impulse responses than oil price shocks. The overwhelming evidence indicates that alternative energy price models, excluding a model containing gasoline prices, outperforms the baseline model containing oil prices for many states, particularly at short-to-mid forecast horizons. In the third chapter, which is coauthored with Lance Bachmeier, we determine whether accounting for oil price endogeneity is important when predicting state-level economic activity. We find that accounting for endogeneity matters for in-sample fit for most states. Specifically, in-sample fit would be improved by using a larger model which contains both regular oil price and endogenous oil price movements. However, we conclude that accounting for endogeneity is not important for out-of-sample forecast accuracy, and a simple model containing only the change in the price of oil produces equally accurate forecasts. Accounting for endogeneity is particularly important in an environment in which rising oil prices were caused by a growing global economy, such as in the years 2004-2007.

Formal savings accounts can be an effective device for households to accumulate assets over time and thus have more funds available to better afford an expensive one-time payment, in the form of either addressing an economic shock or paying for an important life event. I explore this relationship using a field experiment in rural Malawi conducted from 2008-2010, and find that adoption of a formal savings account has no effect on the frequency of economic shocks that a household experiences, nor does it affect how households respond to shocks. However, I find that account adoption does significantly increase the frequency of a household’s expenditures on the life event of payment of secondary school fees. These findings indicate that, given enough time, adoption of a formal savings account allows a household to better accumulate its excess income, and therefore better afford expenditures that involve a decision by the household, as economic shocks tend to be exogenous and payments surrounding life events endogenous. These results support the effectiveness of a policy that extends formal financial services to rural, poor populations who may not have access to such services, as households can use excess funds to finance important life events that help future generations to escape a poverty trap.

We present a mathematical study of two conservative systems in fluid mechanics. First, we study a fragmentation model for sprays. The model takes into account the break-up of spray droplets due to drag forces. In particular, we establish the existence of global weak solutions to a system of incompressible Navier-Stokes equations coupled with a Boltzmann-like kinetic equation. We assume the particles initially have bounded radii and bounded velocities relative to the gas, and we show that those bounds remain as the system evolves. One interesting feature of the model is the apparent accumulation of particles with arbitrarily small radii. As a result, there can be no nontrivial hydrodynamical equilibrium for this system. Next, with an interest in understanding hydrodynamical limits in discontinuous regimes, we study a classical model for shock waves. Specifically, we consider scalar nonviscous conservation laws with strictly convex flux in one spatial dimension, and we investigate the behavior of bounded L² perturbations of shock wave solutions to the Riemann problem using the relative entropy method. We show that up to a time-dependent translation of the shock, the L² norm of a perturbed solution relative to the shock wave is bounded above by the L² norm of the initial perturbation. Finally, we include some preliminary relative entropy estimates which are suitable for a study of shock wave solutions to n x n systems of conservation laws having a convex entropy. / text

This thesis is composed of three chapters, which can be read independently. The first chapter investigates how oil price volatility affects the investment decisions for a panel of Japanese firms. The model is estimated using a system generalized method of moments technique for panel data. The results are presented to show that there is a U-shaped relationship between oil price volatility and Japanese firm investment. The results from subsamples of these data indicate that this U-shaped relationship is more significant for oil-intensive firms and small firms. The second chapter aims to examine the underlying causes of changes in real oil price and their transmission mechanisms in the Japanese stock market. I decompose real oil price changes into three components; namely, oil supply shock, aggregate demand shock and oil-specific demand shock, and then estimate the dynamic effects of each component on stock returns using a structural vector autoregressive (SVAR) model. I find that the responses of aggregate Japanese real stock returns differ substantially with different underlying causes of oil price changes. In the long run, oil shocks account for 43% of the variation in the Japanese real stock returns. The response of Japanese real stock returns to oil price shocks can be attributed in its entirety to the cash flow variations. The third chapter tests the robustness of SVAR and investigates the impact of oil price shocks on the different U.S. stock indices. I find that the responses of real stock returns of alternate stock indices differ substantially depending on the underlying causes of the oil price increase. However, the magnitude and length of the effect depends on the firm size. The response of U.S. stock returns to oil price shocks can be attributed to the variations of expected discount rates and expected cash flows.