📖 失业：类型与自然失业率

Economics

I. Lesson Focus

This lesson defines and classifies the main types of unemployment, derives the natural rate of unemployment, links it to potential GDP and output gaps, and explains Okun’s Law. Candidates must be able to calculate the natural rate, distinguish cyclical unemployment from other types, and understand policy implications when actual unemployment deviates from the natural rate.

II. The Problem

A country reports an unemployment rate of 7.2%, with frictional unemployment at 2.1%, structural at 3.4%, and cyclical at 1.7%. Policymakers must determine whether the economy is at full employment, what the natural unemployment rate is, and whether monetary or fiscal policy should be tightened or eased. This lesson equips candidates to answer these questions accurately on the exam and in practice.

III. Basic Concepts and Measurement of Unemployment

The unemployment rate is the percentage of the labor force that is unemployed. The labor force consists of those who are employed plus those who are actively seeking work. It excludes discouraged workers, students, retirees, and others not participating in the labor market.

The formula is: $$ \text{Unemployment Rate} = \frac{\text{Number of Unemployed}}{\text{Labor Force}} \times 100\% $$

Only individuals who are actively looking for work are counted as unemployed. Discouraged workers who have stopped searching are not in the labor force; therefore, the official unemployment rate understates the true extent of joblessness. This is a frequent CFA trap.

IV. The Four Main Types of Unemployment

1. Frictional Unemployment
   Short-term unemployment arising from normal job transitions and information asymmetries in the labor market. It is a healthy feature reflecting labor mobility.

2. Structural Unemployment
   Longer-term unemployment caused by a mismatch between workers’ skills and job requirements due to technological change, globalization, or shifts in industry demand. It is addressed through retraining and education.

3. Cyclical Unemployment
   Unemployment resulting from fluctuations in the business cycle and insufficient aggregate demand. It rises during recessions and falls during expansions.

4. Classical (Real-Wage) Unemployment
   Occurs when real wages are above the market-clearing level (e.g., due to minimum wage laws or union power), reducing firms’ willingness to hire.

V. The Natural Rate of Unemployment (NRU)

The natural rate of unemployment is the unemployment rate that exists when the economy is in long-run equilibrium and cyclical unemployment is zero. It equals the sum of frictional and structural unemployment rates: $$ \text{Natural Rate of Unemployment (NRU)} = \text{Frictional Unemployment Rate} + \text{Structural Unemployment Rate} $$

The NRU is not constant; it changes with demographics, technology, labor-market institutions (such as unemployment benefits), and labor mobility.

When the actual unemployment rate equals the NRU, the economy is at full employment, and actual GDP equals potential GDP.

VI. Relationship Between Unemployment and the Business Cycle

• Actual unemployment > NRU: Positive cyclical unemployment exists; the economy has a recessionary gap (actual GDP < potential GDP).
• Actual unemployment < NRU: Negative cyclical unemployment; the economy has an inflationary gap (actual GDP > potential GDP) and faces rising inflationary pressure.
• Okun’s Law: For every percentage point that the unemployment rate exceeds the natural rate, actual GDP is approximately 2 percentage points below potential GDP (the coefficient varies slightly across countries).

VII. Link to Potential Output and the Phillips Curve

The natural rate is the unemployment rate at which the long-run Phillips curve is vertical; in the long run there is no trade-off between inflation and unemployment. Short-run Phillips curve trade-offs exist but are eventually eliminated by changes in inflation expectations.

Worked Cases

Case 1: Calculating the Natural Rate

A country has a labor force of 50 million and employment of 46 million. Surveys show frictional unemployment of 0.8 million, structural of 1.1 million, and cyclical of 0.6 million.

Calculations: 1. Total unemployed = 50 – 46 = 4 million 2. Actual unemployment rate = 4 / 50 = 8.0% 3. Natural unemployment rate = (0.8 + 1.1) / 50 = 3.8% 4. Cyclical unemployment rate = 8.0% – 3.8% = 4.2%

Conclusion: The economy is in recession; actual GDP is below potential GDP.

Case 2: Application of Okun’s Law

Natural unemployment rate = 5.5%, actual unemployment rate = 8.5%. Using Okun’s coefficient of 2, estimate the GDP gap.

GDP gap ≈ –2 × (8.5% – 5.5%) = –2 × 3.0% = –6.0%

Actual GDP is therefore about 6% below potential GDP.

Case 3: Policy Scenario

A large increase in the minimum wage pushes real wages above equilibrium, raising the unemployment rate from 5.2% to 7.8%. Frictional unemployment is 2.1%, structural 3.9%, and cyclical 1.8%.

Analysis: - Natural rate = 2.1% + 3.9% = 6.0% - The minimum-wage law primarily increased structural (real-wage) unemployment. - Because actual unemployment exceeds the natural rate, mild cyclical unemployment exists. The central bank may need to adopt expansionary monetary policy to boost aggregate demand.

Traps

Key Formulas

• Unemployment rate = (Unemployed / Labor force) × 100%
• Natural unemployment rate = Frictional rate + Structural rate
• Cyclical unemployment rate = Actual unemployment rate – Natural rate
• Okun’s Law: GDP gap ≈ –β × (Actual unemployment rate – NRU), β ≈ 2
• Full employment: Actual unemployment rate = NRU ⇒ Actual GDP = Potential GDP
• Recessionary gap: Actual unemployment > NRU ⇒ Actual GDP < Potential GDP
• Inflationary gap: Actual unemployment < NRU ⇒ Actual GDP > Potential GDP

Practice Questions

Q1. The most accurate definition of the natural rate of unemployment is the:
A. unemployment rate during a recession
B. sum of the frictional and structural unemployment rates
C. unemployment rate that includes only cyclical unemployment
D. zero unemployment rate

Q2. If a country’s actual unemployment rate is 6.5% and its natural rate is 5.0%, the economy is most likely experiencing:
A. an inflationary gap
B. a recessionary gap
C. full employment
D. zero structural unemployment

Q3. Which type of unemployment typically declines during an economic expansion?
A. Frictional unemployment
B. Structural unemployment
C. Cyclical unemployment
D. Natural unemployment

Q4. A country has a labor force of 8 million and 48,000 unemployed persons, of whom 15,000 are frictionally unemployed and 22,000 are structurally unemployed. The natural unemployment rate is closest to:
A. 4.625%
B. 6.0%
C. 5.0%
D. 0.46%

Q5. An increase in the number of discouraged workers will most likely cause the official unemployment rate to:
A. rise
B. fall
C. remain unchanged while the natural rate rises
D. cause the labor-force participation rate to rise

Q6. According to Okun’s Law, if the natural unemployment rate is 5% and the actual rate is 7% with a coefficient of 2, the output gap is approximately:
A. +4%
B. –4%
C. +2%
D. 0%

Q7. Technological progress that makes workers’ skills obsolete will most likely increase:
A. frictional unemployment
B. structural unemployment
C. cyclical unemployment
D. seasonal unemployment

Q8. When an economy is at full employment:
A. cyclical unemployment is positive
B. actual GDP equals potential GDP
C. the natural unemployment rate is zero
D. the inflation rate must be zero

Answers

Takeaways

• The natural rate of unemployment consists of frictional and structural components and represents the long-run equilibrium unemployment level.
• Cyclical unemployment is the key indicator used to diagnose whether the economy is overheating or in recession.
• When actual unemployment exceeds the natural rate, a recessionary gap exists and GDP is below potential.
• Okun’s Law provides an approximate quantitative link between unemployment deviations and the output gap (coefficient ≈ 2).
• Discouraged workers cause the headline unemployment rate to understate labor-market slack; broader measures (U-4 to U-6) give a fuller picture.
• The natural rate is not fixed; it evolves with labor-market institutions, technology, and demographic changes.