Economics – Exchange rates | e-Consult

Short-Run Effects (Marshall-Lerner & J-Curve):

• Marshall-Lerner (Short-Run): Initially, the depreciation should improve the balance of payments. Exports become cheaper for foreign buyers, increasing export quantities. Imports become more expensive for domestic consumers, decreasing import quantities. The net effect is an improvement in the trade balance. However, the magnitude of this improvement depends on the price elasticities of demand.
• J-Curve (Short-Run): In the short run, the depreciation may initially worsen the balance of payments. Imports rise as they become relatively cheaper, while exports rise more slowly due to time lags in consumer and business responses. This creates the downturn of the 'J'. Eventually, as export quantities respond more strongly to the lower price, the trade balance improves, leading to the upward curve of the 'J'.

Long-Run Effects:

• Marshall-Lerner (Long-Run): In the long run, the Marshall-Lerner theorem suggests that the trade balance will eventually return to a favorable position, assuming that the price elasticities of demand remain constant. If the depreciation has significantly improved competitiveness, this should lead to a sustained increase in exports and a decrease in imports.
• J-Curve (Long-Run): In the long run, the J-curve effect should disappear as consumers and businesses fully adjust to the new exchange rate. The trade balance should improve steadily as export quantities continue to rise and import quantities fall.

Key Assumptions and their Impact on Accuracy:

• Marshall-Lerner Assumption: Positive Price Elasticities: If demand is inelastic, the theorem's predictions may be inaccurate. A depreciation might not lead to a significant increase in exports or a decrease in imports.
• J-Curve Assumption: Time Lags: The length and magnitude of time lags are uncertain. If the lags are very long, the J-curve effect may be weak or non-existent.
• Both Models Assumption: Other Factors Constant: The models assume that other factors influencing the trade balance (e.g., income levels in trading partners, government policies) remain constant. Changes in these factors can significantly alter the outcomes.

Conclusion: The accuracy of the Marshall-Lerner and J-curve models depends heavily on the validity of their underlying assumptions. In reality, these assumptions are often violated, leading to deviations from the predicted outcomes. Therefore, it's crucial to consider a broader range of factors when analyzing the effects of exchange rate changes on the balance of payments.