📖 宏观经济学周测（10 题）

Economics

I. Lesson Focus

II. The Problem

The macroeconomics section comprises roughly 40–50% of the Economics topic on the CFA Level I exam. Candidates frequently lose marks on movements in the AD-AS model, the sustainability of economic growth, types of unemployment and the natural rate, monetary policy transmission mechanisms, the Phillips curve relationship, and fiscal policy multiplier effects. This weekly quiz uses 10 high-quality scenario-based questions to diagnose knowledge gaps while systematically reviewing the central theoretical framework, formula derivations, and real-world applications of macroeconomics, ensuring candidates can quickly identify traps and compute answers accurately under exam pressure.

III. Core Macroeconomic Framework Review

Macroeconomics studies the economy as a whole, focusing on economic growth, inflation, unemployment, and the policy tools available to governments and central banks. The primary analytical tool is the aggregate demand–aggregate supply (AD-AS) model.

The aggregate demand (AD) curve shows the quantity of final goods and services demanded across the economy at different price levels, holding other factors constant. The AD curve slopes downward due to: - The wealth effect - The interest-rate effect - The international trade effect (net-export effect)

The aggregate supply (AS) curve has both short-run (SRAS) and long-run (LRAS) versions. The LRAS is vertical at the level of potential GDP, determined by the quantities of labor, capital, and the level of technology. The SRAS curve slopes upward because wages and input prices are sticky in the short run.

Equilibrium can be short-run or long-run. Deviations from long-run equilibrium create an inflationary gap (actual GDP > potential GDP) or a recessionary gap (actual GDP < potential GDP).

IV. Economic Growth and the Production Function

Sustainable economic growth is determined by the potential GDP growth rate: $$ \text{Potential GDP Growth} \approx \text{Labor Force Growth} + \text{Labor Productivity Growth} $$ Labor productivity growth arises from capital deepening, technological progress, and improvements in human capital.

A simplified Cobb-Douglas production function is: $$ Y = A \cdot K^{\alpha} \cdot L^{1-\alpha} $$ where A is total factor productivity (TFP) and α is capital’s share of output.

V. Unemployment and Inflation

The unemployment rate is calculated as: $$ \text{Unemployment Rate} = \frac{\text{Number of Unemployed}}{\text{Labor Force}} $$ The natural rate of unemployment equals frictional plus structural unemployment.

The Phillips curve shows a short-run trade-off: inflation and unemployment are negatively related when inflation expectations are fixed. The long-run Phillips curve is vertical at the natural unemployment rate, indicating no permanent trade-off.

Inflation is measured by the Consumer Price Index (CPI) or the GDP deflator.

VI. Monetary and Fiscal Policy

Monetary policy transmission mechanism: Policy rate change → market interest rates change → investment and consumption change → aggregate demand changes.

Central bank tools include open-market operations, the discount rate, and reserve requirements.

Fiscal policy uses government spending (G) and taxation. The government spending multiplier in a simple closed economy is: $$ \text{Government Spending Multiplier} = \frac{1}{1 - \text{MPC}} $$ In an open economy with taxes and imports the multiplier is smaller. Crowding-out occurs when government borrowing raises interest rates and reduces private investment, partially offsetting the fiscal expansion.

Worked Cases

Case 1: AD-AS Model Shifts

An economy is in long-run equilibrium. Oil prices then surge sharply while the government simultaneously implements expansionary fiscal policy. Analyze the short-run and long-run effects.

Solution: - The oil-price increase shifts SRAS leftward → higher price level and lower real GDP in the short run (stagflation). - Expansionary fiscal policy shifts AD rightward → further increases the price level but mitigates the fall in GDP. - In the long run, wage adjustments shift SRAS rightward until the economy returns to the LRAS level of potential GDP, but at a permanently higher price level.

Case 2: Potential Growth Rate Calculation

A country has labor-force growth of 1.5%, labor productivity growth of 2.8%, capital-output elasticity α = 0.35, and TFP growth of 1.2%. Estimate potential GDP growth.

Solution: Approximate rule: Potential growth ≈ labor growth + labor productivity growth = 1.5% + 2.8% = 4.3%.
Using the growth form of the production function: $$ \frac{\Delta Y}{Y} \approx \frac{\Delta A}{A} + \alpha \cdot \frac{\Delta K}{K} + (1-\alpha) \cdot \frac{\Delta L}{L} $$ Combining the given figures yields an estimated potential growth rate of approximately 4.1%–4.4%.

Case 3: Comparing Fiscal and Monetary Multipliers

Given MPC = 0.75, marginal propensity to import (MPM) = 0.1, and tax rate t = 0.2, compare the simple fiscal multiplier with the open-economy multiplier that accounts for taxes and imports.

Solution: Simple government-spending multiplier = $1/(1-0.75) = 4$.
Open-economy multiplier = $1/[1 - 0.75(1-0.2) + 0.1] = 1/0.5 = 2$.
Monetary policy affects investment through interest rates and typically has a smaller multiplier than fiscal policy; crowding-out further reduces the realized fiscal multiplier.

Traps

Key Formulas

• AD shift: $\Delta AD = f(\Delta C, \Delta I, \Delta G, \Delta NX)$
• Potential GDP growth ≈ Labor force growth + Labor productivity growth
• Unemployment rate = (Unemployed / Labor force) × 100%
• Simple spending multiplier = $1 / (1 - MPC)$
• Open-economy multiplier = $1 / [1 - MPC(1-t) + MPM]$
• Quantity theory of money: $MV = PY$ (long-run monetary neutrality)
• Short-run Phillips curve: $\pi = \pi^e - \beta(U - U^*)$

Practice Questions

Q1. In the AD-AS model, technological progress is most likely to cause:
A. A leftward shift in both SRAS and LRAS
B. A rightward shift in both SRAS and LRAS
C. A rightward shift in SRAS only
D. A rightward shift in AD only

Q2. If an economy is experiencing a recessionary gap, a central bank would most likely:
A. Raise the reserve requirement
B. Purchase government bonds
C. Raise the discount rate
D. Increase taxes

Q3. Which of the following is most likely a result of cost-push inflation?
A. Real GDP increases and the price level falls
B. Real GDP falls and the price level rises
C. Both real GDP and the price level rise
D. Both real GDP and the price level fall

Q4. A country has a labor force of 50 million, employment of 47 million, and unemployment of 1.5 million. The unemployment rate is closest to:
A. 3.0%
B. 3.1%
C. 6.0%
D. 6.4%

Q5. In the long run, sustained monetary expansion will most likely lead to:
A. A permanently higher level of real GDP
B. A permanently lower unemployment rate
C. A sustained rise in the price level
D. An increase in the natural unemployment rate

Q6. If the marginal propensity to consume is 0.8 and government spending increases by 100 billion with no crowding-out, GDP will increase by:
A. 80 billion
B. 100 billion
C. 400 billion
D. 500 billion

Q7. Which of the following statements about the Phillips curve is most accurate?
A. The long-run Phillips curve slopes downward
B. The short-run Phillips curve illustrates the trade-off when inflation expectations are unchanged
C. Supply shocks do not shift the Phillips curve
D. An increase in the natural unemployment rate shifts the short-run Phillips curve to the left

Q8. An economy has TFP growth of 1.5%, capital-stock growth of 3%, labor-force growth of 2%, and capital’s share of output equal to 0.4. The potential GDP growth rate is closest to:
A. 3.2%
B. 4.1%
C. 4.7%
D. 5.3%

Answers

Takeaways

• The AD-AS model is the central framework for macroeconomic policy analysis; distinguishing short-run from long-run equilibrium is essential
• Potential GDP is determined by labor, capital, and technology; money is neutral in the long run
• The natural rate of unemployment cannot be permanently lowered by demand management; the long-run Phillips curve is vertical
• Fiscal multipliers are reduced by taxes, imports, and crowding-out; realized multipliers are smaller than the simple closed-economy multiplier
• Cost-push inflation produces stagflation while demand-pull inflation occurs with rising output
• Exam questions frequently test the difference between “movement along” versus “shift of” curves; accurate multiplier calculations are required