Chapter 10: Investment and Economic Activity – Study Notes

Investment and Economic Activity

10.1 Long-Run Economic Growth

Long-run economic growth refers to the sustained increase in a nation's productivity, which raises the average standard of living over time. This process is distinct from short-run fluctuations, known as the business cycle, which includes alternating periods of economic expansion and recession.

• Long-run economic growth: The process by which rising productivity increases the average standard of living.

• Business cycle: Short-run swings in the economy, including expansions and recessions.

• Real GDP per capita: The most common measure of average standard of living; it is the amount of production in the economy per person, adjusted for changes in the price level.

• Example: The U.S. real GDP per capita has shown steady growth from 1980 to 2023, with notable dips during recessions.

Potential GDP

Potential GDP is the level of real GDP achieved when all firms are operating at capacity, defined as normal working hours and a normal-sized workforce. It represents the economy's maximum sustainable output.

• Potential GDP: The output level when resources are fully employed at normal rates.

• Potential GDP increases when the labor force expands, capital stock grows, or new technologies are developed.

• In the U.S., potential GDP growth has averaged about 3.2% per year.

• Example: The 2007–2009 recession caused a wider gap between actual and potential GDP.

Rule of 70

The Rule of 70 is a simple way to estimate the number of years required for a variable to double, given a constant annual growth rate.

• Formula: $\text{Doubling Time} = \frac{70}{\text{Growth Rate (in %)}}$

• Example:

  • 1% growth rate: 70 years to double

  • 2% growth rate: 35 years to double

  • 3% growth rate: 23.33 years to double

Financial Markets and Financial Intermediaries

Financial markets facilitate the buying and selling of financial securities, such as stocks and bonds. Financial intermediaries are institutions that connect savers and borrowers.

• Financial security: A document stating the terms under which funds pass from the buyer to the seller.

• Stock: Represents partial ownership in a firm.

• Bond: A promise to repay a fixed amount; essentially a loan from a household to a firm.

• Financial intermediaries: Firms like banks, mutual funds, pension funds, and insurance companies that borrow funds from savers and lend to borrowers.

Three Key Services of the Financial System

The financial system provides essential services that facilitate investment and economic growth.

• Risk sharing: Diversification allows investors to reduce risk while maintaining expected returns.

• Liquidity: Savers can quickly convert investments into cash.

• Information: Prices of financial securities reflect collective beliefs about future returns, helping allocate funds efficiently.

Savings and Investment

Savings represent money set aside in accounts, bonds, stocks, or certificates of deposit, while investment refers to money borrowed for productive use.

• Savings: Money placed in savings accounts, bonds, stocks, or certificates of deposit.

• Investment: Money taken out in the form of a loan.

• National income identity:

  • $Y = C + I + G$

  • $Y - C - G = I$

  Where: $Y$ = National income (GDP) $C$ = Consumption $I$ = Investment $G$ = Government spending

Savings

Total savings in the economy is the sum of private and public savings.

• Private savings ($S_{private}$): Household income not spent, including payments for factors of production and transfer payments, minus consumption and taxes. $S_{private} = Y + TR - C - T$ Where $TR$ = Transfer payments, $T$ = Taxes

• Public savings ($S_{public}$): Government savings, which is the difference between tax revenue and government spending and transfers. $S_{public} = T - G - TR$

• Total savings ($S$): $S = S_{private} + S_{public}$ $S = (Y + TR - C - T) + (T - G - TR)$ $S = Y - C - G$

Apply the Concept: Ebenezer Scrooge and Economic Growth

In A Christmas Carol, Ebenezer Scrooge is depicted as a miser, but his saving behavior can promote economic growth. By saving rather than consuming, resources are directed toward investment, which increases productive capacity and future consumption.

• Example: Scrooge's initial saving behavior allows for greater investment and long-term economic growth, even if it temporarily reduces consumption.

Market for Loanable Funds

The market for loanable funds determines the equilibrium interest rate and quantity of funds available for investment. The supply of loanable funds comes from savings, while the demand comes from investment.

• Supply shifters: Changes in taxes, consumption, income, and government budget.

• Demand shifters: Changes in economic activity, input costs, natural disasters, and technology.

• Graph: The intersection of the supply (S) and demand (D) curves for loanable funds determines the equilibrium interest rate and quantity.

Why Invest and What In?

Investment is crucial for long-term economic growth, as it increases both physical and human capital.

• Physical capital: Machinery, buildings, and equipment used in production.

• Human capital: Skills and education of the workforce.

• Example: Investment shifts the production possibilities frontier (PPF) outward, indicating greater productive capacity.

Summary Table: Savings and Investment Equations

Type	Equation	Description
National Income Identity	$Y = C + I + G$	Total output equals consumption, investment, and government spending
Investment	$I = Y - C - G$	Investment equals output minus consumption and government spending
Private Savings	$S_{private} = Y + TR - C - T$	Household income not spent
Public Savings	$S_{public} = T - G - TR$	Government savings
Total Savings	$S = Y - C - G$	Total savings in the economy

Additional info: The notes have been expanded with academic context and examples for clarity and completeness.