2.3.8

The Consumer Price Index

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The Consumer Price Index

The most commonly cited measure of inflation in the United States is the Consumer Price Index (CPI).

CPI measurement

CPI measurement

  • Government statisticians at the U.S. Bureau of Labor Statistics calculate the CPI based on the prices in a fixed basket of goods and services that represents the purchases of the average family of four.
Shortcomings of CPI

Shortcomings of CPI

  • There are two notable shortcomings of CPI:
    • Substitution bias: An inflation rate calculated using a fixed basket of goods over time tends to overstate the true rise in the cost of living, because it does not take into account that the person can substitute away from goods whose prices rise considerably.
    • Quality/New goods bias: Inflation calculated using a fixed basket of goods over time tends to overstate the true rise in cost of living, because it does not account for improvements in the quality of existing goods or the invention of new goods
Substitution bias explained

Substitution bias explained

  • When the price of a good rises, consumers tend to purchase less of it and to seek out substitutes instead.
  • Conversely, as the price of a good falls, people will tend to purchase more of it.
  • This pattern implies that goods with generally rising prices should tend over time to become less important in the overall basket of goods used to calculate inflation, while goods with falling prices should tend to become more important.
  • The implication of this bias is that CPI tends to overstate the rate of inflation.
Quality/new goods bias explained

Quality/new goods bias explained

  • The arrival of new goods creates problems with respect to the accuracy of measuring inflation.
  • People buy new goods because they tend to offer better value for money than existing goods. Thus, if the price index leaves out new goods, it overlooks one of the ways in which the cost of living is improving.
  • In addition, the price of a new good is often higher when it is first introduced and then declines over time. If the new good is not included in the CPI for some years, until its price is already lower, the CPI may miss counting this price decline altogether.
CPI and core inflation index

CPI and core inflation index

  • Economists typically calculate a core inflation index by taking the CPI and excluding volatile economic variables. In this way, economists have a better sense of the underlying trends in prices that affect the cost of living.
  • Examples of excluded variables include energy and food prices, which can jump around from month to month because of the weather.
Jump to other topics
1

Microeconomics

1.1

Competitive Markets: Demand & Suply

1.1.1Markets & Demand1.1.2Diminishing Marginal Returns1.1.3Supply1.1.4Market Equilibrium1.1.5Price Mechanism1.1.6Consumer & Producer Surplus1.1.7IB Multiple Choice - Demand1.1.8IB Multiple Choice - Supply
1.2

Elasticity

1.2.1Elasticities of Demand1.2.2Factors Affecting Price Elasticity of Demand1.2.3Elasticity of Supply1.2.4Price Elasticity of Supply1.2.5IB Multiple Choice - Price Elasticity of Demand1.2.6IB Multiple Choice - Price Elasticity of Supply1.2.7IB Multiple Choice - Other Elasticities
1.3

Government Intervention

1.3.1Indirect Taxes & Subsidies1.3.2Application Question - Taxing Prices or Quantities1.3.3Subsidies & Price Controls1.3.4Deadweight Loss & Government Intervention1.3.5Elasticity & Tax Incidence1.3.6IB Multiple Choice - Government Intervention
1.4

Market Failure

1.4.1Types of Market Failure1.4.2Introduction to Externalities1.4.3Negative Externalities1.4.4Policy for Negative Externalities1.4.5Positive Externalities1.4.6The Deadweight Welfare Loss of Externalities1.4.7Case Study - The Externalities of Education1.4.8Public Goods & the Free-Rider Problem1.4.9Asymmetric Information1.4.10End of Topic Test - Market Failure1.4.11Application Questions - Market Failure
1.5

HL: Theory of the Firm & Market Structures

1.5.1Theory of the Firm & Market Structures
2

Macroeconomics

2.1

The Level of Overall Economic Activity

2.1.1The Circular Flow of Income2.1.2Defining GDP2.1.3Limitations of GDP2.1.4IB Multiple Choice - Economic Indicators2.1.5Business Cycles2.1.6Output Gaps
2.2

Aggregate Demand & Aggregate Supply

2.2.1The Aggregate Demand Curve2.2.2Components of Aggregate Demand2.2.3Shape of the Aggregate Demand Curve2.2.4Shifts in Aggregate Demand2.2.5IB Multiple Choice - Aggregate Demand2.2.6Short & Long-Run Aggregate Supply2.2.7Alternative Models of LRAS2.2.8Equilibrium in the AD-AS Model2.2.9Output Gaps & the AD-AS Model
2.3

Macroeconomic Objectives

2.3.1Introduction to Unemployment2.3.2Limitations of Unemployment2.3.3Types of Unemployment2.3.4Causes & Impact of Unemployment2.3.5Defining Inflation2.3.6Measuring Inflation2.3.7Use of Index Numbers2.3.8The Consumer Price Index2.3.9Consequences of Inflation2.3.10Causes of Inflation2.3.11Inflation & Unemployment Tradeoff2.3.12The Short-Run Phillips Curve2.3.13The Long-Run Phillips Curve
2.4

Economic Growth, Poverty & Inequality

2.4.1Measuring Economic Growth2.4.2Determinants of Productivity2.4.3Economic Growth & Productivity2.4.4Absolute & Relative Poverty2.4.5Inequality2.4.6Inequality 22.4.7Lorenz Curve2.4.8Government Policy on Poverty2.4.9End of Topic Test - Poverty & Inequality2.4.10Application - Inequality & Poverty
2.5

Fiscal Policy

2.5.1Introduction to Fiscal Policy2.5.2Fiscal Policy and AD-AS Model2.5.3Fiscal Policy Lags2.5.4Automatic Stabilizers2.5.5IB Multiple Choice - Fiscal Policy
2.6

Monetary Policy

2.6.1Objectives of Monetary Policy2.6.2Monetary Policy Implementation2.6.3Monetary Policy & AD-AS Model2.6.4Monetary Policy Lags & Pitfalls
2.7

Supply-Side Policies

2.7.1Supply-Side Policies2.7.2Supply-Side Policies 2
3

The Global Economy

3.1

International Trade

3.1.1Globalisation3.1.2Globalisation for LEDCs3.1.3Globalisation for MEDCs3.1.4Comparative Advantage & Trade3.1.5Protectionism3.1.6Arguments for Protectionism3.1.7Arguments Against Protectionism3.1.8End of Topic Test - Globalisation & Trade3.1.9Case Study - Globalisation & Trade
3.2

Exchange Rates

3.2.1Floating Exchange Rates3.2.2Fixed Exchange Rate3.2.3Effect of a Stronger & Weaker Dollar
3.3

The Balance of Payments

3.3.1Balance of Payments3.3.2Balance of Payments 23.3.3FDI & Reducing a BoP Deficit
3.4

Economic Integration

3.4.1Customs Unions & WTO3.4.2Merged Currency
3.5

Terms of Trade

3.5.1Absolute & Comparative Advantage3.5.2Gains from Trade3.5.3Terms of Trade3.5.4IB Multiple Choice - Comparative Advantage & Trade
3.6

Economic Development

3.6.1Factors Influencing Growth & Development3.6.2International Institutions3.6.3Measures of Development3.6.4Barriers to Development3.6.5Case Study - The Bottom Billion3.6.6End of Topic Test - Emerging & Developing
3.7

The Role of Domestic & International Factors

3.7.1Interventionist Strategies3.7.2Development Strategies3.7.3Development Promotion Policies3.7.4End of Topic Test - Growth & Global Development3.7.5Application Questions -Growth & Global Development
3.8

The Role of International Trade

3.8.1International Institutions3.8.2End of Topic Test - Globalisation & Trade
3.9

The Role of Foreign Aid

3.9.1Aid3.9.2Limitations of Aid3.9.3Support for Aid3.9.4Application Questions - Developing Countries

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Use of Index Numbers

Consequences of Inflation