Explore the connection between the economic indicators and real-world issues. These lessons typically can be done in one class period.


Consumer Price Index (CPI), Costs, Fiscal Policy, Full Employment, Inflation, Monetary Policy, Real Gross Domestic Product (GDP), Unemployment

Current Key Economic Indicators

as of November 30, -0001

Goals of the Case Study

The goals of the Inflation Case Studies are to provide teachers and students:

  • access to easily understood, timely interpretations of monthly announcements of rate of change in prices in the U.S. economy;
  • descriptions of major issues surrounding the data announcements;
  • brief analyses of historical perspectives;
  • questions and activities to use to reinforce and develop understanding of relevant concepts; and
  • a list of publications and resources that may benefit classroom teachers and students interested in exploring inflation.

Information for Teachers

All paragraphs in italics will not appear in the student version of the inflation case study. The original press release can be found at .

This lesson uses several charts and tables. You may use these files to create student reproducables or overhead transparencies for use in your classroom.


The consumer price index (CPI) during the month of May increased by .4 percent (four-tenths of one percent). The rate of increase in the consumer price index over the past twelve months has been 4.2 percent.

In May, the core consumer price index, which excludes energy and food prices, increased by .3 percent (three-tenths of one percent). The core index has increased by 2.4 percent over the last twelve months.

[For teachers - Inflation during May and the last several months appears to be increasing. Inflation, while still relatively low compared to the highest rates the U.S. has experienced, does appear to be increasing.]

Definitions of Inflation

Inflation is a continual increase in the overall level of prices. It is an increase in average prices that lasts at least a few months. The most widely reported measurement of inflation is the consumer price index (CPI). The CPI measures the cost of a fixed set of goods relative to the cost of those same goods in a previous month or year. Changes in the prices of those goods approximate changes in the overall level of prices paid by consumers.

The core consumer price index is the average price of the same set of goods and services, without including food and energy prices, relative to the price of the set without food and energy prices in a previous month or year.

Data Trends

In May, the consumer price index increased by .4 percent, after increasing .6 percent in April and .4 percent in March. In May, energy prices increased once again. The price index for transportation also rose relatively rapidly.

The annual rate of change over the last three months was an increase of 5.7 percent and over the last 12 months, an increase of 4.2 percent. Annual inflation rates from 2002 through 2005 were 2.4, 1.9, 3.3 and 3.4 percent.

The core rate of inflation (increased by .3 percent in May) represents changes in the consumer price index without the influences of changes in the prices of food and energy, which can fluctuate widely from month to month. The increased May index compares to .3 percent increases in the core rate of inflation in each of the previous two months. Core prices increased more slowly in the last two months than the overall index due to rises in prices of energy. The annual rate of increase in prices of energy over the last three months was 35 percent. Energy prices have increased at a 23.6 percent rate over that last 12 months.

Extra attention is given by forecasters to the core index as it tends to show more lasting trends in prices. This month's results provide some evidence that the increase in energy prices over the last several years has not significantly influenced rates of increases in all other prices, but may be beginning to have an upward pressure on other prices. The rapid rise in energy prices may eventually have a significant effect on all other prices in the economy.

Graph 1

Figure 1 shows recent inflation data reported for each month. It is obvious that the monthly inflation figures change a great deal from one month to the next. However, the trend has been an increasing one over the last several months. It is however difficult to tell what the trend over a longer period of time has been.

Figure 2 shows the changes in the core index compared to the changes in the overall CPI. Obviously the changes in prices other than energy and food have been significantly smaller than the changes in the overall index.

Graph 2

Figure 3 shows annual rates of inflation from the 1970s to now. Compared to the rates of inflation in the 1970s and much of the 1980s, the current rate of inflation is low. Few observers would describe the most recent rates, prior to the last few months, as high and they are not, when compared to those of the past thirty years. However, the recent rates of inflation have been increasing and that has caused some concern. See the most recent Federal Reserve case study and the exercises at the end of this case.

Graph 3

Current concerns

The rate of inflation appears to be increasing. The causes are likely to be the effects of relatively low interest rates causing a healthy growth in spending. The second is the rapid rise in petroleum and gasoline prices raising the prices of energy and raising costs of producing a wide variety of goods.

The chairman of the Federal Reserve and others have stated that the present trend in increasing rates of inflation should be met with an increasingly restrictive monetary policy. The current inflation announcement is being discussed as evidence that the Federal Reserve will very likely continue its string of increases in the federal funds interest rate. (See the discussion of monetary policy below and the most recent Federal Reserve case study.)

The Consumer Price Index

The seasonally adjusted consumer price index in May was 201.9. The price index was equal to 100 during the period from 1982 to 1984. The appropriate interpretation of the index is that prices in the market basket of goods and services purchased by the typical consumer increased from the 1982-1984 period to May, 2006 by 101.9 percent. A typical consumer good that cost one dollar in 1983 now costs $2.02.

Inflation is announced and reported in newspapers and television news as percentage changes in the CPI on a monthly basis. For example, the CPI in May was 201.9, compared to 201.0 in April. The increase in prices from May to April was (201.9 - 201) / 201 = .004. That means a monthly inflation rate of .4 percent or four-tenths of one percent.

To convert this into an approximate annual rate, you can simply multiply by 12. This provides us an annual inflation rate of (.4) (12) = 4.8 percent.

Table 1
Month Price Level Monthly Inflation Rate
May 201.9
201.9 - 201 = .004 or .4%

April 201

How the CPI is Calculated

Assume that there are only three goods (instead of goods and services in over 200 categories in the actual calculation) included in the typical consumer's purchases and, in the base or the original year, the goods had prices of $10.00, $20.00, and $30.00. The typical consumer purchased ten of each good.

In the current year, the goods' prices are $11, $24, and $33. Consumers now purchase 12, 8, and 11 of each good.

The CPI for the current year would be the quantities purchased in the market basket in the base year (ten of each good) times their prices in the current year divided by the quantities purchased in the market basket in the base year times their prices in the base year.

Thus [(10 x $11) + (10 x $24) + (10 x $33)] / [( 10 x $10) + (10 x $20) + (10 x $30)] = $680 / $600 = 1.133. That is, prices in the current year are 1.133 times the prices in the original year. Prices have increased on average by 13.3 percent. The quantities are the base year quantities in both the numerator and the denominator.

By convention, the indexes are multiplied by 100 and reported as 113.3 instead of 1.133.

The base year index simply divides the prices in the base year (times the quantities in the base year) by the prices in base year (times the quantities in the base year). The base-year index then is 1.00; or multiplied by 100 equals 100.

CPI Interactive Exercise


Causes of Inflation

Over short periods of time, inflation can be caused by increases in costs or increases in spending. Inflation resulting from an increase in aggregate demand or total spending is called demand-pull inflation . Increases in demand , particularly if production in the economy is near the full-employment level of real GDP, pull up prices. It is not just rising spending. If spending is increasing more rapidly than the capacity to produce, there will be upward pressure on prices.

Inflation can also be caused by increases in costs of major inputs used throughout the economy. This type of inflation is often described as cost-push inflation . Increases in costs push prices up. The most common recent examples are inflationary periods caused largely by increases in the price of oil. Or if employers and employees begin to expect inflation, costs and prices will begin to rise as a result.

Over longer periods of time, that is, over periods of many months or years, inflation is caused by growth in the supply of money that is above and beyond the growth in the demand for money.

Inflation, in the short run and when caused by changes in demand, has an inverse relationship with unemployment. If spending is rising faster than capacity to produce, unemployment is likely to be falling and demand-pull inflation increasing. If spending is rising more slowly than capacity to produce, unemployment will be rising and there will be little demand-pull inflation.

That relationship disappears when inflation is primarily caused by increases in costs. Unemployment and inflation can then rise simultaneously.

Costs of Inflation

Understanding the costs of inflation is not an easy task. There are a variety of myths about inflation. There are debates among economists about some of the more serious problems caused by inflation.

A number of exercises in National Council on Economic Education publications, student workbooks, and textbooks should help students think about the consequences of inflation.

  1. High rates of inflation mean that people and business have to take steps to protect their financial assets from inflation. The resources and time used to do so could be used to produce goods and services of value. Those goods and services given up are a true cost of inflation.
  2. High rates of inflation discourage businesses planning and investment as inflation increases the difficulty of forecasting of prices and costs. As prices rise, people need more dollars to carry out their transactions. When more money is demanded, interest rates increase. Higher interest rates can cause investment spending to fall, as the cost of investing increases. The unpredictability associated with fluctuating interest rates makes customers less likely to sign long-term contracts as well.
  3. The adage "inflation hurts lenders and helps borrowers" only applies if inflation is not expected. For example, interest rates normally increase in response to anticipated inflation. As a result, the lenders receive higher interest payments, part of which is compensation for the decrease in the value of the money lent. Borrowers have to pay higher interest rates and lose any advantage they may have from repaying loans with money that is not worth as much as it was prior to the inflation.
  4. Inflation does reduce the purchasing power of money.
  5. Inflation does redistribute income. On average, individuals' incomes do increase as inflation increases. However, some peoples' wages go up faster than inflation. Other wages are slower to adjust. People on fixed incomes such as pensions or whose salaries are slow to adjust are negatively affected by unexpected inflation.

Discussion questions

Teachers - This is a good opportunity to ask students to discuss each possible cost of inflation. You might divide the class into five small groups and ask each to select one of the above costs, prepare an example that will illustrate the cost, and then present the examples to the rest of the class.

Full employment

Economists define the approximate unemployment rate, at which there are not upward or downward pressures on wages and price, as full employment rate of unemployment. If unemployment falls to level below the full employment rate, there will be upward pressure on wages and prices. If unemployment rises to a very high rate, there will downward pressure on wages and prices or wages and prices will remain steady. In the middle is a level, or more likely a range, where there is not pressure on wages and prices to rise or fall.

Economists do not know for certain what that unemployment rate is, and even if they did, it does change over time. A current consensus estimate is that the full employment rate of unemployment is currently between 4.5 and 5.0 percent of the labor force being unemployed. That is if unemployment were to fall to 4.0 percent of the labor force, there will increased upward pressure on wages and that may cause prices to begin to increase. If unemployment were 6 percent, workers competing for jobs may cause wages to fall. Costs of producing fall and prices may fall. Or at least not increase as rapidly.

Policy discussion question

What should the Federal Reserve do with its monetary policy given this month's consumer price index announcement? Explain why.

Policy question answer.

There are a number of possible issues to discuss with this question. The trend has been one of increasing inflation. That may indicate that the Federal Reserve should slow the growth of the money supply by raising the target federal funds rate (by selling bonds), the discount rate, or the required reserve ratio.

A more advanced approach to the question is that monetary policy has a significant lag. Perhaps the recent more restrictive policy changes are beginning to work and that nothing should be changed with current policy.

In any case, one should caution students to not place too much emphasis on one month change. The trend and what that trend indicates about the future are what are important in deciding policy.

Your class might be divided into three groups with each taking a possible position - a restrictive policy, no change in policy, and a stimulative policy. The latest Federal Reserve, GDP, and unemployment cases might be considered as part of the evidence to be used.