Book cover for Macroeconomics

Macroeconomics

Paul Krugman, Robin Wells

ISBN #9781464110375

4th Edition

265 Questions

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Homework Questions

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Summary
Learning Objectives
Key Concepts
Example Problems
Explanations
Common Mistakes

Summary

This chapter section explains the intrinsic link between savings and investment spending within an economy, emphasizing that total savings must match investment either directly in a closed economy or via adjustments by foreign capital in an open economy. It highlights the pivotal role of the loanable funds market in setting the equilibrium interest rate, which, together with present value calculations, guides investment decisions. Financial systems are essential in facilitating these processes by reducing costs, managing risks, and ensuring liquidity, ultimately supporting sustained economic growth.

Learning Objectives

1

Explain the savings–investment spending identity in both closed and open economies.

2

Describe the role of the loanable funds market in determining the equilibrium interest rate.

3

Analyze how financial systems reduce transaction costs, manage risk, and provide liquidity to support economic growth.

Key Concepts

CONCEPT

DEFINITION

Savings–Investment Spending Identity

A fundamental economic principle stating that total savings in an economy equals total investment spending. In a closed economy, national savings (private savings plus government budget surplus or adjusted for deficit) equals investment, while in an open economy, foreign capital inflows or outflows play a role in balancing savings and investment.

Closed Economy

An economy that does not engage in international trade or capital flows, where total national savings directly equals domestic investment.

Open Economy

An economy that interacts with other economies through trade and capital flows, where foreign capital inflows or outflows adjust the balance between savings and investment.

Loanable Funds Market

A financial market where savers supply funds and investors demand funds. The equilibrium interest rate is determined by the interaction of supply and demand for these loanable funds.

Present Value Calculations

A method used to determine the current value of future cash flows, which helps in making investment decisions by comparing the cost of funds today to the potential benefits in the future.

Financial Systems

Structures and institutions that facilitate the flow of funds in the economy by reducing transaction costs, managing risk through diversification, and providing liquidity to investors and savers.

Example Problems

Example 1

Given the following information about the closed economy of Brittania, what is the level of investment spending and private savings, and what is the budget balance? What is the relationship among the three? Is national savings equal to investment spending? There are no government transfers. $$\begin{array}{ll} \mathrm{GDP}=\$ 1,000 \mathrm{million} & T=\$ 50 \mathrm{million} \\ C=\$ 850 \mathrm{million} & G=\$ 100 \mathrm{million} \end{array}$$

Example 2

Given the following information about the open economy of Regalia, what is the level of investment spending and private savings, and what are the budget balance and net capital inflow? What is the relationship among the four? There are no government transfers. (Hint: net capital inflow equals the value of imports $(I M)$ minus the value of exports $(X) .)$ $\begin{array}{ll}\mathrm{GDP}=\$ 1,000 \text { million } & G=\$ 100 \text { million } \\ C=\$ 850 \text { million } & X=\$ 100 \text { million } \\ T=\$ 50 \text { million } & I M=\$ 125 \text { million }\end{array}$

Example 3

The accompanying table shows the percentage of GDP accounted for by private savings, investment spending, and net capital inflow in the economies of Capsland and Marsalia. Capsland is currently experiencing a positive net capital inflow and Marsalia, a negative net capital outflow. What is the budget balance (as a percentage of GDP) in both countries? Are Capsland and Marsalia running a budget deficit or surplus?

Example 4

Assume the economy is open to capital inflows and outflows and therefore net capital inflow equals imports $(I M)$ minus exports $(X) .$ Answer each of the following questions. a. $X=\$ 125$ million $I M=\$ 80$ million Budget balance $=-\$ 200$ million $I=\$ 350$ million Calculate private savings. b. $X=\$ 85$ million $I M=\$ 135$ million Budget balance $=\$ 100$ million Private savings $=\$ 250$ million Calculate $I$ c. $X=\$ 60$ million $I M=\$ 95$ million Private savings $=\$ 325$ million $I=\$ 300$ million Calculate the budget balance. d. Private savings $=\$ 325$ million $I=\$ 400$ million Budget balance $=\$ 10$ million Calculate $I M-X$

Example 5

The accompanying table, taken from the National Income and Product Accounts Tables, shows the various components of U.S. GDP in 2012 and 2013 in billions of dollars. a. Complete the table by filling in the missing figures. b. For each year, calculate taxes (after transfers) as a percentage of GDP. c. For each year, calculate national savings and private savings.
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Step-by-Step Explanations

QUESTION

How does the savings–investment spending identity function in an economy?

STEP-BY-STEP ANSWER:

Step 1: Define national savings, which comprises private savings and the government’s budget surplus (or accounts for a deficit).
Step 2: In a closed economy, recognize that personal and public sector savings must exactly equal domestic investment spending.
Step 3: In an open economy, understand that any imbalance between savings and domestic investment is adjusted by foreign capital inflows or outflows.
Step 4: Note that this identity underpins the entire mechanism in which capital is mobilized and allocated for growth.
Final Answer: The savings–investment spending identity establishes that total savings, whether generated solely within the economy or supplemented by foreign funds, is equal to the total investment, ensuring that available capital is fully utilized.

Savings–Investment Spending Identity

QUESTION

How does the loanable funds market determine the equilibrium interest rate?

STEP-BY-STEP ANSWER:

Step 1: Identify that the loanable funds market is where savers supply funds and investors demand funds.
Step 2: Analyze how supply and demand interact in this market to find an equilibrium rate.
Step 3: Understand that at this rate, the amount savers are willing to lend equals the amount borrowers want to borrow.
Step 4: Recognize that this equilibrium interest rate influences present value calculations and thus guides investment decisions.
Final Answer: The loanable funds market finds the equilibrium interest rate at the intersection of the supply of and demand for funds, thereby balancing potential borrowers with available savers.

Loanable Funds Market

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Common Mistakes

  • Confusing the savings–investment identity with other financial identities such as the balance of payments.
  • Overlooking the impact of government budget deficits or surpluses in calculating national savings.
  • Assuming that the principles of a closed economy apply directly to an open economy without adjustments for foreign capital flows.
  • Neglecting the importance of the loanable funds market in determining the equilibrium interest rate.
  • Misinterpreting present value calculations and their influence on investment decision-making.