Understanding the Dornbusch Overshooting Model

The question asks what the overshooting model of exchange rate, developed by economist Rudi Dornbusch, attempts to establish. This model is a key concept in international finance and macroeconomics, specifically dealing with how exchange rates react to economic shocks, particularly monetary policy changes.

What is the Dornbusch Overshooting Model?

Rudi Dornbusch developed the overshooting model in the 1970s. It was designed to explain why exchange rates often appear much more volatile than the prices of goods and services. The central idea is that while financial markets (like the foreign exchange market) adjust very quickly, prices for goods and services (like consumer prices) adjust slowly, or are "sticky".

Here's a simplified breakdown of the model's assumptions and mechanism:

• Sticky Prices: Prices of goods and services do not immediately adjust to changes in economic conditions, especially monetary policy shocks.
• Perfect Capital Mobility: Capital can flow freely and instantly across borders, ensuring that interest rates are quickly equalized (adjusted for expected exchange rate changes).
• Asset Market Equilibrium: The foreign exchange market is an asset market, meaning exchange rates adjust rapidly to reflect changes in expected future conditions and interest rate differentials.

How Sticky Prices Lead to Exchange Rate Overshooting

Consider a scenario where the central bank unexpectedly increases the money supply. According to standard economic theory, this should lead to inflation and a depreciation of the currency in the long run. However, because prices are sticky in the short run, the full inflationary effect doesn't happen immediately.

• The increased money supply lowers domestic interest rates (in the short run).
• Lower domestic interest rates make domestic assets less attractive compared to foreign assets.
• Capital flows out, increasing demand for foreign currency and supply of domestic currency in the foreign exchange market.
• The exchange rate depreciates (the domestic currency buys less foreign currency).

Now, here's where overshooting comes in. Because prices are sticky, the expected future exchange rate (which depends on the long-run price level) doesn't adjust fully or instantly. To restore equilibrium in the asset market (specifically, to satisfy the interest rate parity condition, which links interest rate differentials to expected exchange rate changes), the *immediate* depreciation of the exchange rate must be *larger* than the long-run depreciation predicted by the monetary shock alone. The exchange rate "overshoots" its new long-run equilibrium level.

Over time, as goods prices gradually adjust upwards in response to the monetary expansion, the real money supply returns towards its long-run level, domestic interest rates rise back up, and the exchange rate appreciates from its temporarily depreciated, overshot level back towards its less depreciated, long-run equilibrium level.

Analyzing the Options

Let's look at the given options in light of the Dornbusch overshooting model:

1. The fact why the foreign exchange market is never in equilibrium

   This is not what the model establishes. The model assumes that asset markets, including the foreign exchange market, are in equilibrium in the short run. The overshooting is the mechanism through which this equilibrium is achieved under sticky prices.

2. Relationship between sticky prices and volatile exchange rates

   This aligns directly with the core of the model. The model demonstrates that because goods prices are sticky and exchange rates are flexible (asset prices), a shock (like a monetary policy change) causes the flexible exchange rate to overshoot its long-run level in the short run, leading to greater volatility in exchange rates compared to goods prices. This option accurately describes the central relationship explored by the model.

3. The fact that forward rates of exchange are no good predictors of future spot rates of exchange

   While the overshooting model has implications for exchange rate expectations and how they relate to interest rate parity, its primary focus is not on testing the efficiency of forward rates as predictors. That's a related but distinct area of research often linked to concepts like the forward premium puzzle, which came later or is a separate phenomenon.

4. No relationship between sticky prices and volatile exchange rates

   This is contrary to the fundamental conclusion of the Dornbusch model, which explicitly establishes a strong relationship between sticky prices and exchange rate volatility.

Conclusion on Dornbusch Model's Purpose

Based on the analysis of how the model works, it's clear that Rudi Dornbusch's overshooting model was designed precisely to explain the observed phenomenon of high exchange rate volatility and link it to the differential speed of adjustment between asset markets (exchange rates) and goods markets (prices). The model establishes a significant relationship between sticky prices and volatile exchange rates.

Revision Table: Key Concepts

Additional Information on Exchange Rate Models

The Dornbusch overshooting model was a significant step forward from earlier exchange rate models, such as the simple purchasing power parity (PPP) theory, which assumed that exchange rates adjust to equalize the prices of goods across countries. The PPP theory struggled to explain short-term exchange rate movements because it relied on goods prices adjusting quickly. Dornbusch's model addressed this by incorporating the realistic assumption of sticky goods prices alongside rapidly adjusting asset markets.

Other exchange rate models exist, including:

• Monetary Model: Focuses on money supply, demand, and output as determinants of exchange rates, often assuming price flexibility in the long run.
• Portfolio Balance Model: Considers the roles of different assets (like domestic and foreign bonds) and investor preferences in determining exchange rates.
• New Open Economy Macroeconomics Models: More complex models incorporating microfoundations, rational expectations, sticky prices, and other market imperfections to analyze exchange rate dynamics and policy effects.

The Dornbusch model remains influential for its elegant explanation of short-run exchange rate volatility driven by the differential speed of price adjustment.