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Policy lessons from a simple open - economy model


  • Devarajan, Shantayanan
  • Go, Delfin S.
  • Lewis, Jeffrey D.
  • Robinson, Sherman
  • Sinko, Pekka


The authors show how two-sector models can be used to derive policy lessons about adjustment in developing economies. In the past two decades, changes in the external environment and in economic policies have been the key factors in the performance of developing economies. By and large the shocks have involved the external sector: terms-of-trade shocks or cutbacks in foreign capital. The policy responses most commonly proposed have targeted the external sector: depreciating the real exchange rate or reducing distortionary taxes to make the economy more competitive. The authors provide a starting point for analyzing the relation between external shocks and policy responses. Starting from a small, one-country, two-sector, three-good (1-2-3) model, the authors outline how the effects of a foreign capital inflow and terms-of-trade shock can be analyzed. They derive the assumptions underlying the conventional policy recommendation of real exchange rate depreciation in response to adverse shocks. The implications of such trade and fiscal policy instruments as export subsidies, import tariffs, and domestic indirect taxes can also be studied in this framework. The authors show that the standard advice to depreciate the real exchange rate in the wake of an adverse terms-of-trade shock rests on the condition that the income effect of the external shock dominates its substitution effect. But, depending on the characteristics of the economy (for example, the trade elasticities), policy results may run counter to received wisdom. For example, when the substitution effect ofan adverse external shock dominates, real depreciation is inappropriate. An infusion of foreign capital does not necessarily benefit the nontradable sector, as the results of"Dutch disease"models suggest (for example, in the extreme case of nearly infinite substitution elasticity between imports and domestic goods). When import tariffs are significant sources of public revenue, potential revenue losses from tariff cuts must be offset by other revenue sources to maintain the external current account balance. The paper shows a simple way to calculate the necessary tax adjustment. A major advantage of small models is their simplicity. The example in this paper can be solved analytically - either graphically or algebraically. It also can be solved numerically, using such widely available PC-based spreadsheet programs as Excel. The numerical implementation involves only modest data requirements. The data that governments normally release on national income, fiscal, and balance of payments accounts are sufficient.

Suggested Citation

  • Devarajan, Shantayanan & Go, Delfin S. & Lewis, Jeffrey D. & Robinson, Sherman & Sinko, Pekka, 1994. "Policy lessons from a simple open - economy model," Policy Research Working Paper Series 1375, The World Bank.
  • Handle: RePEc:wbk:wbrwps:1375

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    References listed on IDEAS

    1. Benjamin, Nancy C. & Devarajan, Shantayanan & Weiner, Robert J., 1989. "The Dutch disease in a developing country : Oil reserves in Cameroon," Journal of Development Economics, Elsevier, vol. 30(1), pages 71-92, January.
    2. Jaime de MELO & Sherman ROBINSON, 2015. "Product Differentiation And The Treatment Of Foreign Trade In Computable General Equilibrium Models Of Small Economies," World Scientific Book Chapters,in: Modeling Developing Countries' Policies in General Equilibrium, chapter 2, pages 21-41 World Scientific Publishing Co. Pte. Ltd..
    3. Victor Ginsburgh & Jean Waelbroeck, 1981. "Activity analysis and general equilibrium modelling," ULB Institutional Repository 2013/1649, ULB -- Universite Libre de Bruxelles.
    4. Julian M. Alston & Colin A. Carter & Richard Green & Daniel Pick, 1990. "Whither Armington Trade Models?," American Journal of Agricultural Economics, Agricultural and Applied Economics Association, vol. 72(2), pages 455-467.
    5. W. E. G. Salter, 1959. "Internal And External Balance: The Role Op Price And Expenditure Effects," The Economic Record, The Economic Society of Australia, vol. 35(71), pages 226-238, August.
    6. T. W.Swan, 1960. "Economic Control In A Dependent Economy," The Economic Record, The Economic Society of Australia, vol. 36(73), pages 51-66, March.
    7. Mitra, Pradeep, 1992. "The Coordinated Reform of Tariffs and Indirect Taxes," World Bank Research Observer, World Bank Group, vol. 7(2), pages 195-218, July.
    8. Rattso, Jorn, 1982. "Different macroclosures of the original Johansen model and their impact on policy evaluation," Journal of Policy Modeling, Elsevier, vol. 4(1), pages 85-97, March.
    9. Richard Green & Julian M. Alston, 1990. "Elasticities in AIDS Models," American Journal of Agricultural Economics, Agricultural and Applied Economics Association, vol. 72(2), pages 442-445.
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    Cited by:

    1. Auriol, Emmanuelle & Warlters, Michael, 2012. "The marginal cost of public funds and tax reform in Africa," Journal of Development Economics, Elsevier, vol. 97(1), pages 58-72.
    2. Mahmood, Arshad & Marpaung, Charles O.P., 2014. "Carbon pricing and energy efficiency improvement -- why to miss the interaction for developing economies? An illustrative CGE based application to the Pakistan case," Energy Policy, Elsevier, vol. 67(C), pages 87-103.


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