Thesis (M. Com. (Economics)) -- University of Limpopo, 2021 / The main aim of the study is to analyze determinants of sovereign credit ratings (SCRs) for Southern African Development Community (SADC) countries, namely Angola, Botswana, Mozambique, South Africa and Zambia. The analysis is based on the SCRs given by Standard and Poor’s (S&P). The selected explanatory variables are gross domestic product (GDP) per capita, inflation, external debt, foreign direct investment (FDI) inflows and control of corruption for the period 1990-2016, based on annual data. The panel root test results, namely IPS, LLC, ADF Fisher and PP Fisher, show that GDP per capita, external debt and FDI are stationary at 5% level of significance. The Hausman test results indicates that the identified explanatory variable explains 80% of SCRs. The model observed a positive relationship between SCR, inflation and control of corruption. It also observed a negative correlation between SCR, GDP per capita, external debt and FDI. The Pedroni residual cointegration test results indicate that there is no long-run relationship among variables and no autocorrelation as shown by serial correlation LM test results. The study recommends that the selected member states of SADC develop strategic plans for reducing budget deficits. This will help countries to manage their debts, especially foreign currency denoted debt and to attract foreign investment. Keywords: Sovereign credit ratings, fixed effects model, random effects, Hausman test.

Thesis (Ph.D. (Statistics)) -- University of Limpopo, 2022 / Using the ARFIMA (autoregressive and fractionally integrated moving aver age) model extended with sGARCH (standard generalised autoregressive con ditional heteroscedasticity) and ’gjrGARCH (Glosten-Jagannathan-Runkle gen eralised autoregressive conditional heteroscedascity) innovations, fractional in tegration approach and state space model, this study has empirically examined persistency of inflation dynamics of Ghana and South Africa, the only two coun tries in Sub-Saharan Africa with Inflation Targeting (IT) monetary policy. The first part of the analysis employed monthly CPI (Consumer Price Index) in flation series for the period January 1971 to October 2014 obtained from the Bank of Ghana (BoG), and for the period January 1995 to December 2014 ob tained from Statistics South Africa. The second part involves the estimation of threshold effect of inflation on economic growth using annual data obtained from the IMF (International Monetary Fund) database for the period 1981 to 2014, for both countries. Results from the study showed that structural breaks, long memory and non linearities (or regime shifts) are largely responsible for inflation persistence, hence the ever-changing nature of inflation rates of Ghana and South Africa. ARFIMA(3,0.35,1)-‘gjrGARCH(1,1) under Generalised Error Distribution (GED) and ARFIMA(3,0.50,1)-‘gjrGARCH(1,1) under Student-t Distribution (STD) mod els provided the best fit for persistence in the conditional mean (or level) of CPI for Ghana and South Africa, respectively. The results from these models pro vided evidence of time-varying conditional mean and volatility in CPI inflation rates of both countries. The two models also revealed an asymmetric effect of inflationary shocks, where negative shocks appear to have greater impact than positive shocks, in terms of persistence on the conditional mean with time varying volatility. This thesis proposes a model that combines fractional integration with non linear deterministic terms based on the Chebyshev polynomials in time for the analysis of CPI inflation rates of Ghana and South Africa. We tested for non-linear deterministic terms in the context of fractional integration and esti mated the fractional differencing parameters, d to be 1.11 and 1.32 respectively, for the Ghanaian and the South African inflation rates, but the non-linear trends were found to be statistically insignificant in the two series. New ev idence from this thesis depicts that inflation rate of Ghana is highly persistent and non-mean reverting, with an estimated fractional differencing parameter, d > 1.0, and will therefore require some policy action to steer inflation back to stability. However, the South African inflation series was found to be a cyclical process with an order of integration estimated to be d = 0.7, depicting mean reversion, with the length of the cycles approximated to last for 80 months. Finally, the thesis incorporated structural breaks, long memory, non-linearity, and some explanatory variables into a state space model and estimated the threshold effect of inflation on economic growth. The empirical results suggest that inflation below the estimated levels of 9% and 6% for Ghana and South Africa respectively, will be conducive for economic growth. The policy implications of these results for both countries are as follows. First, both series had similar properties responsible for inducing inflation persistence such as structural breaks, non-linearities, long memory and asymmetric re sponse to negatives shocks - but with varied degrees of magnitude. For both countries, the conditional mean and unobserved components such as volatility for both countries were found to be time-varying. This thesis, therefore, recom mends to the BoG and the South African Reserve Bank (SARB) - responsible for monetary policies, and the Finance Ministers of both governments - respon sible for fiscal policies, to take the above-mentioned properties into account in the formulation of their monetary policies. Second, the thesis recommends that the BoG and the SARB consolidate the IT policy, since keeping inflation below the targets set of 9% and 6%, respectively for Ghana and South Africa, will boost economic growth. Third, policymakers could also design measures (monetary and fiscal policies) such as increase in interest rates, credit control, and reduction of unnecessary expenditure, among others, to control inflation due to its adverse effects on market volatility. Even though an increase in interest rates could assist in curtailing the recent and anticipated increase in inflation rates in both countries, where targets have been missed by Ghana and South Africa, it will also be prudent to legislate monetary policies around demand-supply side since the problem of both coun tries appears to be more of a structuralist than a monetarist. It is, therefore, recommended that both countries tighten the IT monetary policy in order to re duce inflation persistence. This will eventually impact on poverty and income distribution with ramifications for economic growth and/or development. The fourth implication of these results is that governments and central banks should be mindful of the actions and decisions they take, in the sense that unguarded decisions and unnecessary alarms could raise uncertainties in the economy, which could, in turn, affect the future trajectory of inflation. Finally, the thesis recommends that governments of both countries strengthen the pri vate sector, which is the engine of growth. For small and open economies such as Ghana and South Africa, this will grow the economy through job creation and restore investor confidence. / National Research Foundation (NRF), Department of Science and Technology (DST), Telkom’s Tertiary Education Support Programme (TESP) and the NRF-DST Centre of Excellence for Mathematical and Statistical Sciences (CoE-MaSS)

An analysis of the current monetary policy framework in South Africa, which followed the exampie of a number of developed countries by implementing an inflation-targeting regime in 2000, is presented. The primary goal of the framework is to establish price stability, with financial stability a secondary objective. However, as has been evident in other countries, price stability does not guarantee financial stability. Movements in asset prices and the development of asset price bubbles have resulted in a number of episodes of financial instability, which negatively impacted on the growth and development of the countries involved. In addition, the majority of these episodes have occurred in periods of low and stable inflation. The dissertation analyses whether monetary policy would be more efficient if asset price movements were incorporated within the inflation-targeting regime. International experience indicates that early intervention of monetary policy can dampen the negative effects that result when an asset price bubble "bursts". However, if the monetary authorities act too early the effects on the economy can be just as disruptive. The literature is scrutinized to establish what the most effective form of monetary policy should be. The results are then transposed within the South African context to establish how the South African Reserve Bank can best ensure both price and financial stability.

This thesis investigates the relationship between expected inflation and nominal interest rates in South Africa and the extent to which the Fisher effect hypothesis holds. The hypothesis, proposed by Fisher (1930), that the nominal rate of interest should reflect movements in the expected rate of inflation has been the subject of much empirical research in many industrialised countries. This wealth of literature can be attributed to various factors including the pivotal role that the nominal rate of interest and, perhaps more importantly, the real rate of interest plays in the economy. The validity of the Fisher effect also has important implications for monetary policy and needs to be considered by central banks. Few studies have been conducted in South Africa to validate this important hypothesis. The analysis uses the 3-month bankers’ acceptance rate and the 10-year government bond rate to proxy both short- and long-term interest rates. The existence of a long-run unit proportional relationship between nominal interest rates and expected inflation is tested using Johansen’s cointegration test. The data is analysed for the period April 2000 to July 2005 as the research aims to establish whether the Fisher relationship holds within an inflation targeting monetary policy framework. The short-run Fisher effect is not empirically verified. This is due to the effects of the monetary policy transmission mechanism and implies that short-term nominal interest rates are a good indication of the stance of monetary policy. A long-run cointegrating relationship is established between long-term interest rates and expected inflation. The long-run adjustment is less than unity, which can be attributed to the credibility of the inflation-targeting framework.

This work examined the optimality of the inclusion of the exchange rate in the reaction function of the Central Bank in an inflation targeting framework. The study attempts to answer the question whether the exchange rate should have an independent role in an open economy Taylor-type rule. To this end, a Taylor-type rule is incorporating the exchange rate is estimated by the cointegration and vector error correction modeling (VECM) using quarterly data for the period of 1995 to 2009. The empirical studies point out the importance of the exchange rates in explaining and forecasting the behaviour of the South African Reserve Bank monetary policy control variable.

Thesis (M. Com.(Economics)) -- University of Limpopo, 2017 / The relationship between unemployment, exchange rate and inflation has been a subject of debate for many years. Given the fact that South Africa is faced with a very low economic growth rate, inflation rate which is likely to go beyond the upper band of 6 percent and a high level of unemployment, policy makers are often faced with the trade-off between unemployment and inflation rate in the country. The purpose of this study is to determine the relationship between exchange rate, unemployment and inflation in South Africa. The study employed Johansen cointegration procedures and the vector error correction model (VECM) to capture the relationship between the variables. The Engle-Granger causality test was also employed to analyse causality amongst the variables. The results of Johansen cointegration test indicate that there is a long-run equilibrium relationship between the variables. The VECM also confirmed the existence of short-run equilibrium relationship between the variables. The nature of the relationship indicates that there is a significant negative relationship between unemployment and inflation in South Africa. This implies that policy makers are been faced with the trade-off between these two variables. The results further indicate that inflation is positively related to exchange rate, meaning a depreciation of the Rand (South African currency) in the foreign exchange market will feed to inflation in the home country. Furthermore, it is also indicated that unemployment is positively related to exchange rate. Meaning, a depreciation of the Rand in the foreign exchange market increases the level of unemployment in South Africa. All the results appeared to be significant. Policies aimed at lowering unemployment and inflation rate are recommended. It is also recommended that policy makers in South Africa take measures to improve the quality of education, skills training and steps to increase the labour intensity of production.

The literature investigating the relationship between stock market returns and inflation is long and has produced diverse findings. This thesis examines the nature of stock–inflation relations in Sub-Saharan countries whose stock markets were established before 1992. Evidence in this thesis shows that in the short term there is a positive relationship between stocks and inflation. Using the Johansen (1988) evidence, a long-run stock–inflation relationship is confirmed only in Nigeria and South Africa, where it is found to be negative. However, accounting for structural breaks provides evidence for a long-run relationship in Botswana, Ghana and Kenya. The evidence of the effects of regimes in the relationship is further supported by a nonparametric cointegration analysis which finds a long-run relation in countries where the Johansen (1988) method had failed. Unexpected inflation is also found to be related to stock returns in Botswana, Ghana, Kenya, Nigeria and Mauritius, which raises concerns about the use of month-end stock data in analysing this relationship. The thesis confirms the existence of hidden inflation in Kenya, Mauritius, Nigeria and Zimbabwe. Imported inflation, interest rates and the exchange rate are found to have useful information about inflation movements in Sub-Saharan Africa.

This study investigated the determinants of inflation in South Africa using quarterly data from 1970Q1 to 2015Q4. The study was motivated by recent trends in domestic inflation that has frequently been at the upper end of the target range of between 3% and 6% and the need to guide inflation related policy since 2008. These recent trends raised concerns regarding the effectiveness of the current monetary policy approach in responding to internal and external factors that are significant in determining domestic inflation. Using Error Correction Model (ECM) modelling techniques, empirical results revealed that inflation expectations, labour costs, government expenditure and import prices are positive determinants, while GDP and exchange rates are negative determinants of inflation. To achieve the macroeconomic policy objective of a stable and low inflation rate for South Africa, more emphasis should be placed on anchoring inflation expectations, which was found to be highly significant in determining inflation. / Economics / M. Com. (Economics)

The thesis consists of four chapters. The introductory chapter clarifies different notions of rationality used by economists and gives a summary of the remainder of the thesis. Chapter 2 proposes an explanation for the common empirical observation of the coexistence of infrequently-changing regular price ceilings and promotion-like price patterns. The results derive from enriching an otherwise standard, albeit stylized, general equilibrium model with two elements. First, the consumer-producer interaction is modeled in the spirit of the price dispersion literature, by introducing oligopolistic markets, consumer search costs and heterogeneity. Second, consumers are assumed to be boundedly-rational: In order to incorporate new information about the general price level, they have to incur a small cognitive cost. The decision whether to re-optimize or act according to the obsolete knowledge about prices is itself a result of optimization. It is shown that in this economy, individual retail prices are capped below the monopoly price, but are otherwise flexible. Moreover, they have the following three properties: 1) An individual price has a positive probability of being equal to the ceiling. 2) Prices have a tendency to fall below the ceiling and then be reset back to the cap value. 3) The ceiling remains constant for extended time intervals even when the mean rate of inflation is positive. Properties 1) and 2) can be associated with promotions and properties 1) and 3) imply the emergence of nominal price rigidity. The results do not rely on any type of direct costs of price adjustment. Instead, price stickiness derives from frictions on the consumers’ side of the market, in line with the results of several managerial surveys. It is shown that the developed theory, compared to the classic menu costs-based approach, does better in matching the stylized facts about the reaction of individual prices to inflation. In terms of quantitative assessment, the model, when calibrated to realistic parameter values, produces median price ceiling durations that match values reported in empirical studies.<p><p>The starting point of the essay in Chapter 3 is the observation that the baseline New-Keynesian model, which relies solely on the notion of infrequent price adjustment, cannot account for the observed degree of inflation sluggishness. Therefore, it is a common practice among macro- modelers to introduce an ad hoc additional source of persistence to their models, by assuming that price setters, when adjusting a price of their product, do not set it equal to its unobserved individual optimal level, but instead catch up with the optimal price only gradually. In the paper, a model of incomplete adjustment is built which allows for explicitly testing whether price-setters adjust to the shocks to the unobserved optimal price only gradually and, if so, measure the speed of the catching up process. According to the author, a similar test has not been performed before. It is found that new prices do not generally match their estimated optimal level. However, only in some sectors, e.g. for some industrial goods and services, prices adjust to this level gradually, which should add to the aggregate inflation sluggishness. In other sectors, particularly food, price-setters seem to overreact to shocks, with new prices overshooting the optimal level. These sectors are likely to contribute to decreasing the aggregate inflation sluggishness. Overall, these findings are consistent with the view that price-setters are boundedly-rational. However, they do not provide clear-cut support for the existence of an additional source of inflation persistence due to gradual individual price adjustment. Instead, they suggest that general equilibrium macroeconomic models may need to include at least two types of production sectors, characterized by a contrasting behavior of price-setters. An additional finding stemming from this work is that the idiosyncratic component of the optimal individual price is well approximated by a random walk. This is in line with the assumptions maintained in most of the theoretical literature. <p><p>Chapter 4 of the thesis has been co-authored by Julia Lendvai. In this paper a full-fledged production economy model with Kahneman and Tversky’s Prospect Theory features is constructed. The agents’ objective function is assumed to be a weighted sum of the usual utility over consumption and leisure and the utility over relative changes of agents’ wealth. It is also assumed that agents are loss-averse: They are more sensitive to wealth losses than to gains. Apart from the changes in the utility, the model is set-up in a standard Real Business Cycle framework. The authors study prices of stocks and risk-free bonds in this economy. Their work shows that under plausible parameterizations of the objective function, the model is able to explain a wide set of unconditional asset return moments, including the mean return on risk-free bonds, equity premium and the Sharpe Ratio. When the degree of loss aversion in the model is additionally assumed to be state-dependent, the model also produces countercyclical risk premia. This helps it match an array of conditional moments and in particular the predictability pattern of stock returns. / Doctorat en Sciences économiques et de gestion / info:eu-repo/semantics/nonPublished

This thesis presents the main results of my research in the field of computational finance and portfolios optimization. We focus on pricing Asian basket options and portfolio problems in the presence of inflation with stochastic interest rates.<p><p>In Chapter 2, we concentrate upon the derivation of bounds for European-style discrete arithmetic Asian basket options in a Black and Scholes framework.We start from methods used for basket options and Asian options. First, we use the general approach for deriving upper and lower bounds for stop-loss premia of sums of non-independent random variables as in Kaas et al. [Upper and lower bounds for sums of random variables, Insurance Math. Econom. 27 (2000) 151–168] or Dhaene et al. [The concept of comonotonicity in actuarial science and finance: theory, Insurance Math. Econom. 31(1) (2002) 3–33]. We generalize the methods in Deelstra et al. [Pricing of arithmetic basket options by conditioning, Insurance Math. Econom. 34 (2004) 55–57] and Vanmaele et al. [Bounds for the price of discrete sampled arithmetic Asian options, J. Comput. Appl. Math. 185(1) (2006) 51–90]. Afterwards we show how to derive an analytical closed-form expression for a lower bound in the non-comonotonic case. Finally, we derive upper bounds for Asian basket options by applying techniques as in Thompson [Fast narrow bounds on the value of Asian options, Working Paper, University of Cambridge, 1999] and Lord [Partially exact and bounded approximations for arithmetic Asian options, J. Comput. Finance 10 (2) (2006) 1–52]. Numerical results are included and on the basis of our numerical tests, we explain which method we recommend depending on moneyness and time-to-maturity<p><p>In Chapter 3, we propose some moment matching pricing methods for European-style discrete arithmetic Asian basket options in a Black & Scholes framework. We generalize the approach of Curran M. (1994) [Valuing Asian and portfolio by conditioning on the geometric mean price”, Management science, 40, 1705-1711] and of Deelstra G. Liinev J. and Vanmaele M. (2004) [Pricing of arithmetic basket options by conditioning”, Insurance: Mathematics & Economics] in several ways. We create a framework that allows for a whole class of conditioning random variables which are normally distributed. We moment match not only with a lognormal random variable but also with a log-extended-skew-normal random variable. We also improve the bounds of Deelstra G. Diallo I. and Vanmaele M. (2008). [Bounds for Asian basket options”, Journal of Computational and Applied Mathematics, 218, 215-228]. Numerical results are included and on the basis of our numerical tests, we explain which method we recommend depending on moneyness and<p>time-to-maturity.<p><p>In Chapter 4, we use the stochastic dynamic programming approach in order to extend<p>Brennan and Xia’s unconstrained optimal portfolio strategies by investigating the case in which interest rates and inflation rates follow affine dynamics which combine the model of Cox et al. (1985) [A Theory of the Term Structure of Interest Rates, Econometrica, 53(2), 385-408] and the model of Vasicek (1977) [An equilibrium characterization of the term structure, Journal of Financial Economics, 5, 177-188]. We first derive the nominal price of a zero coupon bond by using the evolution PDE which can be solved by reducing the problem to the solution of three ordinary differential equations (ODE). To solve the corresponding control problems we apply a verification theorem without the usual Lipschitz assumption given in Korn R. and Kraft H.(2001)[A Stochastic control approach to portfolio problems with stochastic interest rates, SIAM Journal on Control and Optimization, 40(4), 1250-1269] or Kraft(2004)[Optimal Portfolio with Stochastic Interest Rates and Defaultable Assets, Springer, Berlin].<p><p><p> / Doctorat en Sciences / info:eu-repo/semantics/nonPublished