Exchange-Rate Determination and Forecasting

Introduction and Context

The exchange rate is the price of one currency expressed in another. It affects the domestic-currency cost of imports, the foreign-currency price of exports, international investment returns, inflation, debt servicing and the profitability of foreign-trade transactions. For a trading firm, an exchange-rate forecast is not merely an economic prediction; it supports quotations, budgeting, pricing, hedging and decisions about payment currency.

Exchange rates are determined by interacting goods-market, financial-market and institutional forces. Purchasing power parity links currencies to relative price levels; interest rate parity links spot and forward exchange rates to interest-rate differences; the Fisher effect connects nominal interest rates with expected inflation; and monetary and balance-of-payments approaches explain how money supply, income, trade flows and capital movements influence currency value. No single model forecasts accurately in every period. Professional forecasting therefore combines economic theory, current data, market information and scenario analysis.

Learning Objectives

By the end of this chapter, the learner should be able to:

• explain how exchange rates are quoted and interpreted;
• apply absolute and relative purchasing power parity;
• use covered and uncovered interest-rate parity;
• explain the Fisher effect and its international implications;
• analyse monetary and balance-of-payments determinants;
• interpret macroeconomic indicators relevant to foreign exchange;
• distinguish fundamental, technical and scenario-based forecasting;
• identify forecasting limitations and design a practical foreign-exchange risk response.

Essential Terminology and Exchange-Rate Conventions

A spot rate applies to immediate currency delivery, normally within the market convention for spot settlement. A forward rate is agreed today for delivery on a future date. A direct quote states domestic currency per unit of foreign currency; an indirect quote states foreign currency per unit of domestic currency. If a domestic importer sees USD 1 = ₹83, the direct quotation from the Indian perspective is ₹83 per dollar.

The base currency is written first in a currency pair and the quote currency second. In EUR/USD = 1.0900, one euro costs 1.0900 US dollars. An appreciation of the base currency means that more units of the quote currency can be obtained for one unit of the base currency. A pip is a standard small quotation increment, although its value depends on the currency pair and market convention.

The exchange-rate change, expressed as a proportion, is commonly calculated as:

This formula requires the same quotation convention in both observations. Under a direct quote of domestic currency per foreign currency, an increase normally indicates domestic-currency depreciation, while a decrease indicates appreciation.

Purchasing Power Parity

Absolute Purchasing Power Parity

Purchasing power parity (PPP) proposes that identical tradable goods should cost the same after conversion into a common currency, assuming no transport costs, tariffs, taxes, market segmentation or quality differences. Let S be the domestic-currency price of one unit of foreign currency, P be the domestic price level and P* the foreign price level. Absolute PPP is:

The units are domestic currency per foreign currency because P is measured in domestic currency and P* in foreign currency. Absolute PPP is a long-run benchmark rather than a precise short-run law. Non-traded services, trade barriers, distribution margins and differing consumption baskets cause systematic deviations.

Relative Purchasing Power Parity

Relative PPP focuses on changes rather than price-level equality. If π is domestic inflation and π* is foreign inflation, the exact relationship implied by the price-level form is:

Thus the expected percentage change in the direct exchange rate is approximately:

The approximation is suitable when inflation rates and exchange-rate changes are modest. The exact form should be preferred for high inflation or large differentials.

Worked Example: Relative PPP

Suppose the current rate is ₹83.00 per US dollar. Expected Indian inflation is 6% and US inflation is 2%. Relative PPP gives:

S₁ = 83 × (1.06 ÷ 1.02) = ₹86.25 approximately

The rupee is predicted to depreciate by approximately 3.92% against the dollar. The result is a theoretical benchmark; actual rates may differ because of capital flows, risk premia, productivity changes and policy intervention.

The Balassa–Samuelson effect provides one explanation for persistent PPP deviations. Faster productivity growth in a country’s tradable-goods sector can raise wages throughout the economy, including in non-traded services. The country’s price level may rise and its currency may appreciate in real terms without an equivalent loss of competitiveness in tradables.

Interest-Rate Parity

Interest-rate parity explains the relationship between interest rates, spot rates and forward rates. It is central to pricing forward contracts and evaluating whether an apparent interest-rate advantage is offset by exchange-rate conditions.

Covered Interest-Rate Parity

Covered interest-rate parity (CIP) assumes that an investor hedges the future exchange rate with a forward contract. With S quoted as domestic currency per foreign currency, F as the forward rate for the same maturity, i_d as the domestic interest rate and i_f as the foreign interest rate:

For annual rates over a fraction t of a year, assuming simple interest:

The formula assumes comparable maturity, no transaction costs, unrestricted capital movement, ability to borrow and lend at the stated rates, and absence of credit or sovereign-risk differences. In practice, funding costs, collateral requirements and market segmentation can produce a CIP basis.

Worked Example: Forward Rate

If the spot rate is ₹83.00/US$, the one-year Indian interest rate is 7% and the US rate is 4%, then:

F = 83 × (1.07 ÷ 1.04) = ₹85.40 approximately

The forward premium on the dollar is approximately 2.89%. This does not necessarily represent a forecast of the future spot rate; it is primarily an arbitrage-consistent price for covered transactions.

Uncovered Interest-Rate Parity

Uncovered interest-rate parity (UIP) concerns an unhedged investment. If E(S₁) is the expected future spot rate:

Equivalently, for modest rates:

UIP requires risk-neutral investors and no risk premium. Empirically, it often performs poorly over short horizons; high-interest-rate currencies have sometimes failed to depreciate as much as UIP predicts. This phenomenon is associated with the forward-premium puzzle and may reflect risk premia, expectations errors and changing market regimes.

The Fisher Effect and International Fisher Effect

The Fisher effect separates the nominal interest rate into a real return and expected inflation. The exact relationship is:

where i is the nominal interest rate, r is the real interest rate and πᵉ is expected inflation. Therefore:

The approximation i ≈ r + πᵉ is acceptable when rates are relatively small. The cross-product r × πᵉ is omitted in that approximation.

The international Fisher effect combines the Fisher effect with expected real-rate equality. It suggests that a currency with a higher nominal interest rate will depreciate by approximately the interest-rate differential, because the higher rate reflects higher expected inflation. This is conceptually related to UIP but is not identical: the Fisher effect concerns nominal and real interest rates, while UIP concerns expected exchange-rate changes and financial returns.

Monetary Approaches to Exchange-Rate Determination

The monetary approach treats the exchange rate as the relative price of two monies. A simple money-demand function is:

where Mᵈ is nominal money demand, P is the price level, Y is real income and i is the nominal interest rate. A common log-linear representation is:

Lowercase letters denote natural logarithms, k measures the income sensitivity of real money demand and λ measures interest sensitivity. Money-market equilibrium requires real money supply to equal real money demand.

In a flexible-price monetary model, an increase in domestic money supply, holding output and interest conditions constant, tends to raise the domestic price level and depreciate the domestic currency. Higher domestic real income increases money demand and may appreciate the currency in the short run if money supply is unchanged. Higher domestic interest rates reduce money demand in the simple specification, although the overall exchange-rate effect depends on whether the interest-rate movement reflects monetary tightening, inflation expectations or a risk premium.

The overshooting model explains why exchange rates can move more sharply than their long-run level following a monetary shock. Financial markets adjust rapidly, while goods prices are sticky. An expansionary monetary shock can therefore cause an immediate depreciation larger than the eventual long-run depreciation, followed by partial appreciation as goods prices adjust. Overshooting is a model implication, not a universal empirical rule.

Balance-of-Payments Approach

The balance of payments records transactions between residents and the rest of the world. In simplified form:

The exact presentation depends on the accounting system and treatment of reserves. A current-account deficit must be financed by net capital or financial inflows, reserve changes or an adjustment in other components. A surplus tends to create upward pressure on the currency when it reflects sustained demand for exports and foreign demand for domestic assets.

Important determinants include:

• Trade balance: Export demand and import demand affect currency demand and supply.
• Terms of trade: A rise in export prices relative to import prices can improve national income, although the effect depends on quantities and import dependence.
• Capital flows: Foreign direct investment may be relatively persistent, whereas portfolio flows can reverse quickly.
• External debt: Debt-service obligations increase demand for foreign currency and expose the economy to refinancing risk.
• Reserves and intervention: A central bank may buy or sell foreign currency, affecting liquidity and the exchange rate.
• Confidence and risk: Political uncertainty, sovereign risk and banking stress can trigger capital outflows even when trade data appear favourable.

The balance-of-payments approach is especially useful for medium- and long-term analysis, but an accounting surplus does not automatically imply appreciation. The financial account may dominate the current account, and valuation changes can alter reported positions.

Macroeconomic Indicators for Foreign-Exchange Analysis

A professional analyst should interpret indicators jointly rather than react mechanically to one release.

The analyst should distinguish the actual, consensus forecast and previous release. Markets commonly respond more to the surprise relative to expectations than to the level alone. Forward-looking central-bank communication can be more influential than a historical indicator.

Forecasting Exchange Rates

Fundamental Forecasting

Fundamental forecasting estimates the exchange rate from macroeconomic variables, financial conditions and institutional developments. A practical workflow is:

1. Define the currency pair, quotation convention and forecast horizon.
2. Establish a baseline using inflation, interest rates, growth, fiscal conditions and external balances.
3. Identify policy reaction functions, such as the likely central-bank response to inflation.
4. Assess capital flows, commodity exposure, intervention and political risk.
5. Compare the result with market-implied forward prices and consensus forecasts.
6. Express the forecast as a range with explicit assumptions.

Fundamental analysis is most useful for strategic and medium-term decisions. Its weaknesses include uncertain causal relationships, data revisions, model instability and the difficulty of timing market reactions.

Technical Forecasting

Technical analysis uses past prices, returns, volume and market patterns. Common tools include moving averages, support and resistance levels, trend lines, momentum indicators and volatility measures. A simple moving average over n observations is:

where S is the observed exchange rate and n is the window length. A moving average smooths data but lags turning points. It does not establish economic causation. Technical rules should be tested out of sample, adjusted for transaction costs and evaluated for stability across periods.

A useful risk measure is the standard deviation of returns. If r_t is the exchange-rate return and r̄ is its sample mean, sample volatility is:

The units are return units per observation period. Annualisation requires a stated frequency and an assumption about return independence; for daily data it is often approximated by multiplying daily volatility by √252, but this is not reliable during volatility clustering.

Scenario-Based Forecasting

Scenario analysis is preferable when uncertainty is structural or when probability estimates are unreliable. Construct a small set of internally consistent narratives, such as:

• Baseline: gradual disinflation and stable policy convergence;
• Adverse domestic scenario: fiscal stress, capital outflow and currency depreciation;
• External shock scenario: global recession or commodity-price disruption;
• Favourable scenario: stronger productivity, export growth and stable inflows.

Each scenario should specify assumptions, indicators to monitor, an exchange-rate range, commercial consequences and management actions. Scenarios are not forecasts with false precision; they are conditional maps for decisions.

Combining Forecasts

A robust process may combine a fundamental estimate, a technical signal and a market-implied benchmark. A weighted forecast can be written as:

where F, T and M are the fundamental, technical and market estimates and the weights satisfy w_F + w_T + w_M = 1. The weights must be justified, periodically validated and changed when evidence indicates a regime shift. Combining models does not eliminate model risk.

Applied Case: Hedging an Import Payment

This is an illustrative case.

Background

An Indian machinery importer must pay US$500,000 in six months. The current spot rate is ₹83.00/US$. The treasurer expects the rupee to weaken because domestic inflation is projected at 6%, US inflation at 2%, and the domestic central bank may ease rates. However, a global slowdown could reduce dollar demand and support the rupee.

Problem

The firm must prepare a rupee budget while avoiding a decision based on a single uncertain forecast. A six-month forward quotation is ₹84.20/US$. The firm’s internal scenarios are:

The probability-weighted expected spot payment is:

0.25×40,000,000 + 0.50×42,500,000 + 0.25×45,000,000 = ₹42,500,000

Analysis and Approach

A full forward hedge fixes the payment at:

500,000 × 84.20 = ₹42,100,000

The forward eliminates uncertainty but prevents the firm from benefiting if the rupee appreciates. The expected unhedged payment in the planning distribution is ₹42.5 million, but the adverse scenario reaches ₹45 million. A treasury committee might therefore hedge a core portion, for example 70%, and retain flexibility for the balance, subject to policy and liquidity constraints. The 70% forward commitment would be US$350,000 and the fixed rupee cost would be ₹29.47 million; the remaining US$150,000 would remain exposed or be hedged with an option.

The decision should also consider the importer’s risk tolerance, cash-flow capacity, option premium, accounting treatment, supplier terms and the possibility that the payment date changes. The forward rate must not be described as an unbiased forecast merely because it is market-determined.

Outcome and Learning Points

The appropriate outcome is a documented hedge policy rather than a claim to know the future spot rate. The case demonstrates that forecasting supports, but does not replace, risk management. A sound process defines exposure, separates forecast from hedge price, uses scenarios, records assumptions and reviews performance against the original decision—not merely against the most favourable alternative outcome.

Limitations, Governance and Contemporary Practice

Exchange-rate models can fail during crises, regime changes and policy surprises. Structural breaks, thin markets, intervention, capital controls and geopolitical events may invalidate historical relationships. Forecast accuracy should be assessed using a benchmark such as the random walk, not only by comparing one model with another. Common measures include mean absolute error and root mean squared error:

MAE is in the same units as the forecast variable; RMSE penalises large errors more heavily. Comparisons must use the same sample, horizon and data vintage.

Governance requires separation of dealing, confirmation, settlement and valuation duties; authorised limits; counterparty assessment; independent price verification; documentation of hedge effectiveness; and compliance with applicable accounting, reporting and foreign-exchange regulations. Forecast models should not encourage speculative positions that exceed the underlying commercial exposure.

Modern treasury teams use real-time data, algorithmic dashboards, machine-learning models and alternative data such as news sentiment. These tools can identify nonlinear patterns, but they also create risks of overfitting, data leakage, opaque decisions and unstable performance. AI outputs should be explainable enough for review, tested against simple benchmarks and supervised by qualified professionals. Human accountability remains essential.

Best-Practice Forecasting Protocol

1. Use a consistent quotation convention and verify all units.
2. Separate short-term trading signals from long-term economic estimates.
3. Compare PPP, interest parity and monetary indicators rather than treating one as decisive.
4. Distinguish observed data, expectations and assumptions.
5. Report ranges and confidence or scenario conditions, not unjustified point precision.
6. Include transaction costs, liquidity, risk premia and policy intervention.
7. Back-test technical and quantitative methods without look-ahead bias.
8. Update forecasts when new information changes the economic regime.
9. Link forecasts to exposure limits, hedge ratios and business decisions.
10. Maintain an audit trail of data, models, approvals and outcomes.

Chapter Summary

Exchange rates are relative prices shaped by goods markets, money markets, interest rates, expectations, capital flows and policy. Absolute PPP links exchange rates to relative price levels, while relative PPP links exchange-rate changes approximately to inflation differentials. Covered interest-rate parity determines the arbitrage-consistent relationship between spot, forward and interest rates; uncovered parity is an expectations relationship affected by risk premia. The Fisher effect connects nominal interest rates with real returns and expected inflation.

Monetary models emphasise relative money supplies, income and interest rates, while balance-of-payments analysis focuses on trade, capital flows, reserves and external sustainability. Fundamental forecasting uses macroeconomic analysis; technical forecasting uses market history; and scenario forecasting addresses uncertainty through conditional narratives. Because every approach has limitations, professional practice combines models, validates them against benchmarks and connects forecasts to disciplined treasury governance and hedging decisions.

Key Terms

Exchange rate: Price of one currency in terms of another.

Spot rate: Exchange rate for near-immediate delivery.

Forward rate: Agreed rate for currency delivery at a future date.

Direct quotation: Domestic currency per unit of foreign currency.

Purchasing power parity: Theory linking currencies to relative price levels.

Absolute PPP: Equality of converted price levels.

Relative PPP: Relationship between inflation differentials and exchange-rate changes.

Covered interest parity: No-arbitrage relationship using a forward hedge.

Uncovered interest parity: Expected-return relationship without a forward hedge.

Fisher effect: Relationship between nominal interest, real interest and expected inflation.

International Fisher effect: Predicted currency movement based on nominal interest differentials.

Money demand: Desired holdings of money as a function of income, prices and interest.

Overshooting: Short-run exchange-rate movement beyond its long-run response.

Balance of payments: Systematic record of international economic transactions.

Current account: Record of goods, services, income and transfers.

Capital and financial flows: Cross-border investment and financing transactions.

Fundamental forecasting: Forecasting from economic and financial determinants.

Technical forecasting: Forecasting from historical market data and patterns.

Scenario analysis: Conditional assessment of alternative future environments.

Risk premium: Additional expected return required for bearing risk.

Review Questions

Short Answer Questions

1. What is the difference between a direct and an indirect exchange-rate quotation?
2. State the relative PPP relationship and explain when its approximation is appropriate.
3. Why does covered interest-rate parity use a forward contract?
4. Distinguish the Fisher effect from uncovered interest-rate parity.
5. Identify two limitations of technical exchange-rate forecasting.

Long Answer Questions

1. Explain absolute and relative purchasing power parity, including their assumptions and practical limitations.
2. Derive and interpret the covered interest-rate parity relationship for a direct quotation.
3. Discuss how monetary conditions and balance-of-payments developments jointly influence exchange rates.
4. Compare fundamental, technical and scenario-based forecasting for a foreign-trade firm.
5. Explain the governance requirements for using exchange-rate forecasts in treasury decisions.

Analytical / Application Questions

1. A currency is quoted at ₹82 per US dollar. Domestic expected inflation is 7% and US expected inflation is 3%. Use relative PPP to estimate the future rate and explain why the actual rate may differ.
2. A firm must pay US$200,000 in three months. Compare the risk characteristics of remaining unhedged, using a forward contract, and using an option. Identify information needed before selecting a strategy.
3. A country has a current-account deficit, rising inflation, falling reserves and increasing political uncertainty, but its policy interest rate has recently increased. Construct baseline and adverse exchange-rate scenarios and explain why the rate increase alone does not determine the currency outcome.

Multiple Choice Questions with Answers

Question 1

Under a direct quotation of domestic currency per foreign currency, an increase in the quoted rate generally indicates:

A. Domestic-currency appreciation

B. Domestic-currency depreciation

C. A fall in foreign inflation

D. A reduction in the forward premium

Correct Answer: B. Domestic-currency depreciation

Question 2

If the current spot rate is ₹83/US$, domestic inflation is 6% and foreign inflation is 2%, relative PPP estimates the future rate as approximately:

A. ₹80.00/US$

B. ₹83.00/US$

C. ₹86.25/US$

D. ₹89.00/US$

Correct Answer: C. ₹86.25/US$

Question 3

Covered interest-rate parity is principally an arbitrage relationship involving:

A. Spot and forward rates with domestic and foreign interest rates

B. Only inflation and unemployment

C. Only export and import quantities

D. Stock prices and dividend yields

Correct Answer: A. Spot and forward rates with domestic and foreign interest rates

Question 4

If a domestic nominal interest rate is 8% and expected inflation is 3%, the exact real interest rate is approximately:

A. 3.00%

B. 4.85%

C. 5.00%

D. 11.00%

Correct Answer: B. 4.85%

Question 5

Which condition is most directly associated with exchange-rate overshooting?

A. Instant adjustment of all goods prices

B. Sticky goods prices and rapidly adjusting financial markets

C. A permanent trade embargo

D. Absence of capital markets

Correct Answer: B. Sticky goods prices and rapidly adjusting financial markets

Question 6

Which item is recorded primarily in the current account of the balance of payments?

A. Foreign direct investment purchase

B. A central-bank reserve transaction

C. Export of services

D. Purchase of a foreign government bond

Correct Answer: C. Export of services

Question 7

A forward rate should generally be interpreted as:

A. A guaranteed unbiased prediction of the future spot rate

B. An arbitrage-consistent price for covered currency delivery

C. The official inflation forecast

D. The central bank’s required exchange rate

Correct Answer: B. An arbitrage-consistent price for covered currency delivery

Question 8

A 20-day moving average of exchange rates is most accurately described as:

A. A measure that smooths observations but may lag turning points

B. A guaranteed measure of intrinsic value

C. A direct estimate of purchasing power parity

D. A measure requiring no historical data

Correct Answer: A. A measure that smooths observations but may lag turning points

Question 9

Which practice creates look-ahead bias in a forecasting back-test?

A. Using only information available on each forecast date

B. Including later-revised information that was unavailable at the forecast date

C. Allowing for transaction costs

D. Comparing against a random-walk benchmark

Correct Answer: B. Including later-revised information that was unavailable at the forecast date

Question 10

The main purpose of scenario-based exchange-rate forecasting is to:

A. Eliminate all uncertainty

B. Produce one exact rate with no assumptions

C. Link alternative assumptions to conditional outcomes and actions

D. Replace all financial controls

Correct Answer: C. Link alternative assumptions to conditional outcomes and actions