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Principles of Macroeconomics 2e

5.2 Polar Cases of Elasticity and Constant Elasticity

Principles of Macroeconomics 2e5.2 Polar Cases of Elasticity and Constant Elasticity
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Table of contents
  1. Preface
  2. 1 Welcome to Economics!
    1. Introduction
    2. 1.1 What Is Economics, and Why Is It Important?
    3. 1.2 Microeconomics and Macroeconomics
    4. 1.3 How Economists Use Theories and Models to Understand Economic Issues
    5. 1.4 How To Organize Economies: An Overview of Economic Systems
    6. Key Terms
    7. Key Concepts and Summary
    8. Self-Check Questions
    9. Review Questions
    10. Critical Thinking Questions
  3. 2 Choice in a World of Scarcity
    1. Introduction to Choice in a World of Scarcity
    2. 2.1 How Individuals Make Choices Based on Their Budget Constraint
    3. 2.2 The Production Possibilities Frontier and Social Choices
    4. 2.3 Confronting Objections to the Economic Approach
    5. Key Terms
    6. Key Concepts and Summary
    7. Self-Check Questions
    8. Review Questions
    9. Critical Thinking Questions
    10. Problems
  4. 3 Demand and Supply
    1. Introduction to Demand and Supply
    2. 3.1 Demand, Supply, and Equilibrium in Markets for Goods and Services
    3. 3.2 Shifts in Demand and Supply for Goods and Services
    4. 3.3 Changes in Equilibrium Price and Quantity: The Four-Step Process
    5. 3.4 Price Ceilings and Price Floors
    6. 3.5 Demand, Supply, and Efficiency
    7. Key Terms
    8. Key Concepts and Summary
    9. Self-Check Questions
    10. Review Questions
    11. Critical Thinking Questions
    12. Problems
  5. 4 Labor and Financial Markets
    1. Introduction to Labor and Financial Markets
    2. 4.1 Demand and Supply at Work in Labor Markets
    3. 4.2 Demand and Supply in Financial Markets
    4. 4.3 The Market System as an Efficient Mechanism for Information
    5. Key Terms
    6. Key Concepts and Summary
    7. Self-Check Questions
    8. Review Questions
    9. Critical Thinking Questions
    10. Problems
  6. 5 Elasticity
    1. Introduction to Elasticity
    2. 5.1 Price Elasticity of Demand and Price Elasticity of Supply
    3. 5.2 Polar Cases of Elasticity and Constant Elasticity
    4. 5.3 Elasticity and Pricing
    5. 5.4 Elasticity in Areas Other Than Price
    6. Key Terms
    7. Key Concepts and Summary
    8. Self-Check Questions
    9. Review Questions
    10. Critical Thinking Questions
    11. Problems
  7. 6 The Macroeconomic Perspective
    1. Introduction to the Macroeconomic Perspective
    2. 6.1 Measuring the Size of the Economy: Gross Domestic Product
    3. 6.2 Adjusting Nominal Values to Real Values
    4. 6.3 Tracking Real GDP over Time
    5. 6.4 Comparing GDP among Countries
    6. 6.5 How Well GDP Measures the Well-Being of Society
    7. Key Terms
    8. Key Concepts and Summary
    9. Self-Check Questions
    10. Review Questions
    11. Critical Thinking Questions
    12. Problems
  8. 7 Economic Growth
    1. Introduction to Economic Growth
    2. 7.1 The Relatively Recent Arrival of Economic Growth
    3. 7.2 Labor Productivity and Economic Growth
    4. 7.3 Components of Economic Growth
    5. 7.4 Economic Convergence
    6. Key Terms
    7. Key Concepts and Summary
    8. Self-Check Questions
    9. Review Questions
    10. Critical Thinking Questions
    11. Problems
  9. 8 Unemployment
    1. Introduction to Unemployment
    2. 8.1 How Economists Define and Compute Unemployment Rate
    3. 8.2 Patterns of Unemployment
    4. 8.3 What Causes Changes in Unemployment over the Short Run
    5. 8.4 What Causes Changes in Unemployment over the Long Run
    6. Key Terms
    7. Key Concepts and Summary
    8. Self-Check Questions
    9. Review Questions
    10. Critical Thinking Questions
    11. Problems
  10. 9 Inflation
    1. Introduction to Inflation
    2. 9.1 Tracking Inflation
    3. 9.2 How to Measure Changes in the Cost of Living
    4. 9.3 How the U.S. and Other Countries Experience Inflation
    5. 9.4 The Confusion Over Inflation
    6. 9.5 Indexing and Its Limitations
    7. Key Terms
    8. Key Concepts and Summary
    9. Self-Check Questions
    10. Review Questions
    11. Critical Thinking Questions
    12. Problems
  11. 10 The International Trade and Capital Flows
    1. Introduction to the International Trade and Capital Flows
    2. 10.1 Measuring Trade Balances
    3. 10.2 Trade Balances in Historical and International Context
    4. 10.3 Trade Balances and Flows of Financial Capital
    5. 10.4 The National Saving and Investment Identity
    6. 10.5 The Pros and Cons of Trade Deficits and Surpluses
    7. 10.6 The Difference between Level of Trade and the Trade Balance
    8. Key Terms
    9. Key Concepts and Summary
    10. Self-Check Questions
    11. Review Questions
    12. Critical Thinking Questions
    13. Problems
  12. 11 The Aggregate Demand/Aggregate Supply Model
    1. Introduction to the Aggregate Supply–Aggregate Demand Model
    2. 11.1 Macroeconomic Perspectives on Demand and Supply
    3. 11.2 Building a Model of Aggregate Demand and Aggregate Supply
    4. 11.3 Shifts in Aggregate Supply
    5. 11.4 Shifts in Aggregate Demand
    6. 11.5 How the AD/AS Model Incorporates Growth, Unemployment, and Inflation
    7. 11.6 Keynes’ Law and Say’s Law in the AD/AS Model
    8. Key Terms
    9. Key Concepts and Summary
    10. Self-Check Questions
    11. Review Questions
    12. Critical Thinking Questions
    13. Problems
  13. 12 The Keynesian Perspective
    1. Introduction to the Keynesian Perspective
    2. 12.1 Aggregate Demand in Keynesian Analysis
    3. 12.2 The Building Blocks of Keynesian Analysis
    4. 12.3 The Phillips Curve
    5. 12.4 The Keynesian Perspective on Market Forces
    6. Key Terms
    7. Key Concepts and Summary
    8. Self-Check Questions
    9. Review Questions
    10. Critical Thinking Questions
  14. 13 The Neoclassical Perspective
    1. Introduction to the Neoclassical Perspective
    2. 13.1 The Building Blocks of Neoclassical Analysis
    3. 13.2 The Policy Implications of the Neoclassical Perspective
    4. 13.3 Balancing Keynesian and Neoclassical Models
    5. Key Terms
    6. Key Concepts and Summary
    7. Self-Check Questions
    8. Review Questions
    9. Critical Thinking Questions
    10. Problems
  15. 14 Money and Banking
    1. Introduction to Money and Banking
    2. 14.1 Defining Money by Its Functions
    3. 14.2 Measuring Money: Currency, M1, and M2
    4. 14.3 The Role of Banks
    5. 14.4 How Banks Create Money
    6. Key Terms
    7. Key Concepts and Summary
    8. Self-Check Questions
    9. Review Questions
    10. Critical Thinking Questions
    11. Problems
  16. 15 Monetary Policy and Bank Regulation
    1. Introduction to Monetary Policy and Bank Regulation
    2. 15.1 The Federal Reserve Banking System and Central Banks
    3. 15.2 Bank Regulation
    4. 15.3 How a Central Bank Executes Monetary Policy
    5. 15.4 Monetary Policy and Economic Outcomes
    6. 15.5 Pitfalls for Monetary Policy
    7. Key Terms
    8. Key Concepts and Summary
    9. Self-Check Questions
    10. Review Questions
    11. Critical Thinking Questions
    12. Problems
  17. 16 Exchange Rates and International Capital Flows
    1. Introduction to Exchange Rates and International Capital Flows
    2. 16.1 How the Foreign Exchange Market Works
    3. 16.2 Demand and Supply Shifts in Foreign Exchange Markets
    4. 16.3 Macroeconomic Effects of Exchange Rates
    5. 16.4 Exchange Rate Policies
    6. Key Terms
    7. Key Concepts and Summary
    8. Self-Check Questions
    9. Review Questions
    10. Critical Thinking Questions
    11. Problems
  18. 17 Government Budgets and Fiscal Policy
    1. Introduction to Government Budgets and Fiscal Policy
    2. 17.1 Government Spending
    3. 17.2 Taxation
    4. 17.3 Federal Deficits and the National Debt
    5. 17.4 Using Fiscal Policy to Fight Recession, Unemployment, and Inflation
    6. 17.5 Automatic Stabilizers
    7. 17.6 Practical Problems with Discretionary Fiscal Policy
    8. 17.7 The Question of a Balanced Budget
    9. Key Terms
    10. Key Concepts and Summary
    11. Self-Check Questions
    12. Review Questions
    13. Critical Thinking Questions
    14. Problems
  19. 18 The Impacts of Government Borrowing
    1. Introduction to the Impacts of Government Borrowing
    2. 18.1 How Government Borrowing Affects Investment and the Trade Balance
    3. 18.2 Fiscal Policy and the Trade Balance
    4. 18.3 How Government Borrowing Affects Private Saving
    5. 18.4 Fiscal Policy, Investment, and Economic Growth
    6. Key Terms
    7. Key Concepts and Summary
    8. Self-Check Questions
    9. Review Questions
    10. Critical Thinking Questions
    11. Problems
  20. 19 Macroeconomic Policy Around the World
    1. Introduction to Macroeconomic Policy around the World
    2. 19.1 The Diversity of Countries and Economies across the World
    3. 19.2 Improving Countries’ Standards of Living
    4. 19.3 Causes of Unemployment around the World
    5. 19.4 Causes of Inflation in Various Countries and Regions
    6. 19.5 Balance of Trade Concerns
    7. Key Terms
    8. Key Concepts and Summary
    9. Self-Check Questions
    10. Review Questions
    11. Critical Thinking Questions
    12. Problems
  21. 20 International Trade
    1. Introduction to International Trade
    2. 20.1 Absolute and Comparative Advantage
    3. 20.2 What Happens When a Country Has an Absolute Advantage in All Goods
    4. 20.3 Intra-industry Trade between Similar Economies
    5. 20.4 The Benefits of Reducing Barriers to International Trade
    6. Key Terms
    7. Key Concepts and Summary
    8. Self-Check Questions
    9. Review Questions
    10. Critical Thinking Questions
    11. Problems
  22. 21 Globalization and Protectionism
    1. Introduction to Globalization and Protectionism
    2. 21.1 Protectionism: An Indirect Subsidy from Consumers to Producers
    3. 21.2 International Trade and Its Effects on Jobs, Wages, and Working Conditions
    4. 21.3 Arguments in Support of Restricting Imports
    5. 21.4 How Governments Enact Trade Policy: Globally, Regionally, and Nationally
    6. 21.5 The Tradeoffs of Trade Policy
    7. Key Terms
    8. Key Concepts and Summary
    9. Self-Check Questions
    10. Review Questions
    11. Critical Thinking Questions
    12. Problems
  23. A | The Use of Mathematics in Principles of Economics
  24. B | The Expenditure-Output Model
  25. Answer Key
    1. Chapter 1
    2. Chapter 2
    3. Chapter 3
    4. Chapter 4
    5. Chapter 5
    6. Chapter 6
    7. Chapter 7
    8. Chapter 8
    9. Chapter 9
    10. Chapter 10
    11. Chapter 11
    12. Chapter 12
    13. Chapter 13
    14. Chapter 14
    15. Chapter 15
    16. Chapter 16
    17. Chapter 17
    18. Chapter 18
    19. Chapter 19
    20. Chapter 20
    21. Chapter 21
  26. References
  27. Index

Learning Objectives

By the end of this section, you will be able to:

  • Differentiate between infinite and zero elasticity
  • Analyze graphs in order to classify elasticity as constant unitary, infinite, or zero

There are two extreme cases of elasticity: when elasticity equals zero and when it is infinite. A third case is that of constant unitary elasticity. We will describe each case. Infinite elasticity or perfect elasticity refers to the extreme case where either the quantity demanded (Qd) or supplied (Qs) changes by an infinite amount in response to any change in price at all. In both cases, the supply and the demand curve are horizontal as Figure 5.4 shows. While perfectly elastic supply curves are for the most part unrealistic, goods with readily available inputs and whose production can easily expand will feature highly elastic supply curves. Examples include pizza, bread, books, and pencils. Similarly, perfectly elastic demand is an extreme example. However, luxury goods, items that take a large share of individuals’ income, and goods with many substitutes are likely to have highly elastic demand curves. Examples of such goods are Caribbean cruises and sports vehicles.

Two graphs, side by side, show that perfectly elastic demand and perfectly elastic supply are both straight, horizontal lines.
Figure 5.4 Infinite Elasticity The horizontal lines show that an infinite quantity will be demanded or supplied at a specific price. This illustrates the cases of a perfectly (or infinitely) elastic demand curve and supply curve. The quantity supplied or demanded is extremely responsive to price changes, moving from zero for prices close to P to infinite when prices reach P.

Zero elasticity or perfect inelasticity, as Figure 5.5 depicts, refers to the extreme case in which a percentage change in price, no matter how large, results in zero change in quantity. While a perfectly inelastic supply is an extreme example, goods with limited supply of inputs are likely to feature highly inelastic supply curves. Examples include diamond rings or housing in prime locations such as apartments facing Central Park in New York City. Similarly, while perfectly inelastic demand is an extreme case, necessities with no close substitutes are likely to have highly inelastic demand curves. This is the case of life-saving drugs and gasoline.

The two graphs show that zero elasticity of supply and zero elasticity of demand are straight, vertical lines.
Figure 5.5 Zero Elasticity The vertical supply curve and vertical demand curve show that there will be zero percentage change in quantity (a) demanded or (b) supplied, regardless of the price.

Constant unitary elasticity, in either a supply or demand curve, occurs when a price change of one percent results in a quantity change of one percent. Figure 5.6 shows a demand curve with constant unit elasticity. Using the midpoint method, you can calculate that between points A and B on the demand curve, the price changes by 66.7% and quantity demanded also changes by 66.7%. Hence, the elasticity equals 1. Between points B and C, price again changes by 66.7% as does quantity, while between points C and D the corresponding percentage changes are again 66.7% for both price and quantity. In each case, then, the percentage change in price equals the percentage change in quantity, and consequently elasticity equals 1. Notice that in absolute value, the declines in price, as you step down the demand curve, are not identical. Instead, the price falls by $8.00 from A to B, by a smaller amount of $4.00 from B to C, and by a still smaller amount of $2.00 from C to D. As a result, a demand curve with constant unitary elasticity moves from a steeper slope on the left and a flatter slope on the right—and a curved shape overall.

This graph shows how a demand curve with unitary elasticity at all points will always be a curved line.
Figure 5.6 A Constant Unitary Elasticity Demand Curve A demand curve with constant unitary elasticity will be a curved line. Notice how price and quantity demanded change by an identical percentage amount between each pair of points on the demand curve.

Unlike the demand curve with unitary elasticity, the supply curve with unitary elasticity is represented by a straight line, and that line goes through the origin. In each pair of points on the supply curve there is an equal difference in quantity of 30. However, in percentage value, using the midpoint method, the steps are decreasing as one moves from left to right, from 28.6% to 22.2% to 18.2%, because the quantity points in each percentage calculation are getting increasingly larger, which expands the denominator in the elasticity calculation of the percentage change in quantity.

Consider the price changes moving up the supply curve in Figure 5.7. From points D to E to F and to G on the supply curve, each step of $1.50 is the same in absolute value. However, if we measure the price changes in percentage change terms, using the midpoint method, they are also decreasing, from 28.6% to 22.2% to 18.2%, because the original price points in each percentage calculation are getting increasingly larger in value, increasing the denominator in the calculation of the percentage change in price. Along the constant unitary elasticity supply curve, the percentage quantity increases on the horizontal axis exactly match the percentage price increases on the vertical axis—so this supply curve has a constant unitary elasticity at all points.

This graph shows that a supply curve with unitary elasticity at all points will always be a straight line.
Figure 5.7 A Constant Unitary Elasticity Supply Curve A constant unitary elasticity supply curve is a straight line reaching up from the origin. Between each pair of points, the percentage increase in quantity supplied is the same as the percentage increase in price.
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