The role of exchange rate in small open economies : the case of Tanzania

Doctoral Thesis


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University of Cape Town

This thesis addresses exchange rate behaviour in a de-facto partially dollarized economy. Over the past two decades the Tanzanian Shilling has been increasingly displaced by the United States dollar. This change has been prompted by instability of the local currency, and by the practices of foreign firms, which have used a dual pricing system at rates disadvantageous to the local currency. The implications of Tanzania's dollarization are traced through three related investigations: whether theTanzania Shilling to United States Dollar exchange rate overshoots, whether it has impacted the monetary transmission mechanism, and whether dollarization has substantively affected the pattern of Tanzania's foreign trade. The first study uses the Structural Vector Autoregression to test if the overshooting hypothesis holds for the TZS-USD exchange rate.The results suggest that foreign currency deposits are encouraged by the volatility of the exchange rate.In addition it is noted that the exchange rate demonstrates delayed overshooting, while a contractionary monetary policy leads to appreciation in the exchange rate for at least a year before returning to equilibrium. The determinants of the exchange rate in Tanzania are trade openness, real interest differentials, labour productivity and government expenditure. The second study uses a Bayesian Vector Autoregression to investigate the monetary transmission mechanism in the presence of dollarization. The results indicate that positive shocks on the interest rate contract money supply, which leads to lower output growth and inflation, while the exchange rate appreciates. The degree of dollarization also has a negative impact on the monetary supply of the local currency, as the central bank seeks to maintain a relatively constant rate of total money supply. This has the effect of lowering the inflation and interest rates, and is also associated with further depreciation of the exchange rate. The positive shock on the exchange rate (depreciation) is associated with an increase in dollarization.The aggregate demand shock fuels inflation and, in Tanzania's case, it has increased money supply, due to the persistent demand for real monetary balances. The third study uses a Dynamic Stochastic General Equilibrium to describe the conduct of monetary policy in a small, open, and partially dollarized Tanzanian economy. The structure of the model incorporates the expectations of agents and the dynamic relationships are explained in terms of structural representations that characterize the behaviour of the firm, household and central bank. The parameters in the model are estimated with Bayesian techniques, after it has been applied to Tanzanian data. The effects of individual shocks, including those that may be used to describe the conduct of monetary policy, are then considered. These simulations suggest that despite the existence of partial dollarization in the Tanzanian economy, monetary policy has important, short-term, real effects. The fourth study uses an Autoregressive Distributed Lag approach to investigate the short and long run exchange rate sensitivity of foreign trade. Principal components analysis is also used to reduce the dimension of the dataset. It finds evidence that the depreciation of the Shilling typically has an immediate positive impact on the trade balance, and exchange rate depreciation increases the trade balance in both the short and long run. However, exports show signs that support the J-curve hypothesis, though the associated parameters are not significant. Imports are not reduced by a rise in the Shilling, as traditional theory would suggest. This is ascribed to the country's de-facto partial dollarization. Since over 40 per cent of money supply arecurrently held in dollar denominated accounts, trade is largely immune to domestic currency fluctuations. This study also notesthat the use of foreign currency has tended to rise during periods of substantial economic growth. Although no causality is argued, this does suggest that the parallel use of foreign and domestic currencies is not detrimental to Tanzania's economic growth.

Includes bibliographical references