ECOS2025 Chap.3 Exchange Rates, Capital Flows and Debt
Exchange Rates, Capital Flows and Debt
This chapter joins three macro tools used throughout the country cases. It begins with exchange-rate quotation and purchasing-power parity, moves to saving, investment and international capital flows, and finishes with public-debt dynamics. The emphasis is direction discipline: define units, separate identities from causes and check the sign of every policy effect.
What this chapter covers
- 01
Exchange-rate quotes
- 02
Purchasing-power parity
- 03
Fixed-rate intervention
- 04
Saving-investment identity
- 05
Uncovered interest parity
- 06
Debt-ratio dynamics
Worked example · free
Reading an external financing gap
- +1Compute S minus I as 24 minus 29, which equals negative 5% of GDP.
- +1The identity implies a current-account deficit of 5% of GDP.
- +1State that the deficit is matched by net capital inflow and evaluate what the finance supports.
Key terms
- Nominal exchange rate
- The price of one currency in units of another, whose direction depends on quotation convention.
- Purchasing-power parity
- A benchmark linking exchange-rate changes to relative inflation through the law of one price.
- Capital inflow
- Net external financing associated with a current-account deficit under the balance-of-payments identity.
- Primary deficit
- Government spending excluding interest minus revenue, a direct driver of public-debt accumulation.
Exchange Rates, Capital Flows and Debt FAQ
Why do exchange-rate direction errors happen so often?
Students name appreciation before writing the quotation units. A rise has opposite meanings under foreign-per-domestic and domestic-per-foreign conventions, so units must come before the direction word.
Does a current-account deficit prove weak policy?
No. It records investment exceeding saving and matching capital inflow. Evaluation depends on what the inflow finances, whether returns exceed repayment costs and how vulnerable financing is to reversal.
What raises pressure on the public-debt ratio?
A weaker primary balance, a higher real interest rate and slower output growth all increase pressure. The debt stock and the annual deficit must remain separate in the explanation.
Why can nominal depreciation fail to improve competitiveness?
Domestic inflation may offset the nominal change, leaving the real exchange rate little improved. The answer should state the real-rate definition and compare domestic with foreign prices before claiming a gain.
What does uncovered interest parity compare?
It compares expected returns on domestic and foreign assets after allowing for the expected exchange-rate movement. Define the quotation convention because the sign of expected appreciation depends on it.
How should a fixed exchange rate be analysed?
Identify the official rate, the market pressure and the central bank transaction required to maintain the gap. Then consider reserves, interest rates and whether the policy changes the real rate.
How should a currency claim be connected to an East Asian development argument?
Begin with the quote convention and regime, then separate the nominal movement from relative inflation and the real exchange rate. Trace the channel through export prices, imported inputs, balance sheets or capital flows rather than assuming depreciation always raises growth.
Japan after the Plaza Accord requires domestic policy and financial responses to explain persistence; China requires evidence about intervention and production capability. Finish by checking reserves, foreign-currency liabilities and maturity, because a competitiveness gain can coexist with a more fragile debt position.
Exam move
Keep a one-page direction sheet and build it from units rather than arrows learned by memory. Write one quotation as foreign currency per domestic unit and the inverse as domestic currency per foreign unit. Under each, record what a numerical rise means for the domestic currency and test yourself with a fresh value. Add the real exchange rate used in the lectures and note that inflation can offset a nominal depreciation.
Explain purchasing-power parity from the law of one price, then list the frictions that make it a benchmark rather than an immediate forecast. On a second section, write the saving-investment identity and translate positive and negative S minus I into current-account and capital-flow language. Test each with one numerical example and state what the identity cannot establish about causation.
A deficit can reflect weak saving, strong investment, fiscal policy or another mechanism, so never treat the sign as a complete welfare verdict. Add uncovered interest parity with every symbol defined, then practise the fixed-rate case and one expected-appreciation case. For public debt, separate the annual primary balance from the inherited debt stock.
Make a three-arrow diagram showing how the primary deficit, real interest rate and output growth change debt pressure. Apply the arrows to Japan and explain why deflation can matter even when nominal interest rates are low. Write two original short answers: one in which a central bank weakens its currency under a managed regime, and another in which a capital inflow finances productive investment but creates rollover risk.
For each, underline the quotation convention, regime and mechanism. Finish with a sign audit. Every use of appreciation, depreciation, surplus, deficit, inflow, outflow, higher r or lower g must be justified from the printed units or equation. If a direction word is unsupported, replace it only after reconstructing the relationship. This habit is faster than correcting a reversed argument at the end of an exam response.
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