Mankiw Principles of Economics (3rd ed)

F Y I

What Is in

CPI’s Basket?

largest category the typical

cost of shelter cent), and household The next largest which includes

and so on. The

beverages; this includes food at home (9 percent), food away from home (6 percent), and alcoholic beverages (1 percent). Next are medical care at 6 percent, recreation at 6 percent, apparel at 5 percent, and education and communication at 5 percent. This last category includes, for example, college tuition and personal computers.

Also included in the figure, at 5 percent of spending, is a category for other goods and services. This is a catchall for things consumers buy that do not naturally fit into the other categories, such as cigarettes, haircuts, and funeral expenses.

16% Food and beverages

6%

6%

Recreation

5% 5% 5%

Medical care

Other goods

and services Education and Apparel communication

Figure 23-1

THE TYPICAL BASKET OF GOODS AND SERVICES. This

figure shows how the typical consumer divides his spending among various categories of goods and services. The Bureau of Labor Statistics calls each percentage the “relative importance” of the category.

SOURCE: Bureau of Labor Statistics.

inflation rate

the percentage change in the price index from the preceding period

services in each year is divided by the price of the basket in the base year, and this ratio is then multiplied by 100. The resulting number is the consumer price index.

In the example in the table, the year 2001 is the base year. In this year, the basket of hot dogs and hamburgers costs $8. Therefore, the price of the basket in all years is divided by $8 and multiplied by 100. The consumer price index is 100 in 2001. (The index is always 100 in the base year.) The consumer price index is 175 in 2002. This means that the price of the basket in 2002 is 175 percent of its price in the base year. Put differently, a basket of goods that costs $100 in the base year costs $175 in 2002. Similarly, the consumer price index is 250 in 2003, indicating that the price level in 2003 is 250 percent of the price level in the base year.

5.Compute the Inflation Rate. The fifth and final step is to use the consumer price index to calculate the inflation rate, which is the percentage change in the price index from the preceding period. That is, the inflation rate between two consecutive years is computed as follows:

Inflation rate in year 2 CPI in year 2 CPI in year 1 100.

In our example, the inflation rate is 75 percent in 2002 and 43 percent in 2003.

Although this example simplifies the real world by including only two goods, it shows how the Bureau of Labor Statistics (BLS) computes the consumer price index and the inflation rate. The BLS collects and processes data on the prices of thousands of goods and services every month and, by following the five foregoing steps, determines how quickly the cost of living for the typical consumer is rising. When the bureau makes its monthly announcement of the consumer price index, you can usually hear the number on the evening television news or see it in the next day’s newspaper.

In addition to the consumer price index for the overall economy, the BLS calculates several other price indexes. It reports the index for specific regions within the country (such as Boston, New York, and Los Angeles) and for some narrow categories of goods and services (such as food, clothing, and energy). It also calculates the producer price index, which measures the cost of a basket of goods and services bought by firms rather than consumers. Because firms eventually pass on their costs to consumers in the form of higher consumer prices, changes in the producer price index are often thought to be useful in predicting changes in the consumer price index.

PROBLEMS IN MEASURING THE COST OF LIVING

The goal of the consumer price index is to measure changes in the cost of living. In other words, the consumer price index tries to gauge how much incomes must rise in order to maintain a constant standard of living. The consumer price index, however, is not a perfect measure of the cost of living. Three problems with the index are widely acknowledged but difficult to solve.

The first problem is called substitution bias. When prices change from one year to the next, they do not all change proportionately: Some prices rise by more than others. Consumers respond to these differing price changes by buying less of the goods whose prices have risen by large amounts and by buying more of the goods whose prices have risen less or perhaps even have fallen. That is, consumers substitute toward goods that have become relatively less expensive. Yet the consumer price index is computed assuming a fixed basket of goods. By not taking into account the possibility of consumer substitution, the index overstates the increase in the cost of living from one year to the next.

Let’s consider a simple example. Imagine that in the base year, apples are cheaper than pears, and so consumers buy more apples than pears. When the Bureau of Labor Statistics constructs the basket of goods, it will include more apples than pears. Suppose that next year pears are cheaper than apples. Consumers will naturally respond to the price changes by buying more pears and fewer apples. Yet, when computing the consumer price index, the Bureau of Labor Statistics uses a fixed basket, which in essence assumes that consumers continue buying the now expensive apples in the same quantities as before. For this reason, the index will measure a much larger increase in the cost of living than consumers actually experience.

producer price index

a measure of the cost of a basket of goods and services bought by firms

IN THE NEWS

Shopping for the CPI

Labor Statistics employees who gather the information that is fed into the monthly Consumer Price Index. . . .

Mrs. Bloom’s travails sometimes read like a detective novel. Each month, she covers 900 miles in her beat-up Geo Prizm (three accidents in the past 18 months) to visit about 150 sites. Her mission: to record the prices of certain items, time and again. If prices change, she needs to find out why. Each month, some 90,000 prices are shipped to Washington, plugged into a computer, scrutinized, aggregated, adjusted for seasonal ups or downs, and then spit out as the monthly CPI report.

Choosing what to price—for example, the “regular” or “fancy” baby parakeet—can seem arbitrary. After consulting surveys that track consumer buying habits, the labor statistics bureau

selects popular stores and item cate- gories—say, women’s tops. The pricetaker then asks a store employee to help zero in on an item of the price-taker’s choosing. They narrow to the size of the top, its style (short-sleeve, long-sleeve, tank, or turtleneck), and so on; items that generate the most revenue in a category have the best chance of getting picked.

Shoppers know that relying on employees for anything can be chancy. At a downtown Chicago department store (the government doesn’t disclose

THE INTRODUCTION OF NEW PRODUCTS

BIASES THE CPI.

The second problem with the consumer price index is the introduction of new goods. When a new good is introduced, consumers have more variety from which to choose. Greater variety, in turn, makes each dollar more valuable, so consumers need fewer dollars to maintain any given standard of living. Yet because the consumer price index is based on a fixed basket of goods and services, it does not reflect this change in the purchasing power of the dollar.

Again, let’s consider an example. When VCRs were introduced, consumers were able to watch their favorite movies at home. Compared to going to a movie theater, the convenience is greater and the cost is less. A perfect cost-of-living index would reflect the introduction of the VCR with a decrease in the cost of living. The consumer price index, however, did not decrease in response to the introduction of the VCR. Eventually, the Bureau of Labor Statistics did revise the basket of goods

names) price-taker Mary Ann Latter squints at a sale sign above an ivory shell blouse. “Save 45%–60% when you take an additional 30% off permanently reduced merchandise. Markdown taken at register,” the sign says.

Confused, Ms. Latter asks a clerk to scan the item. There is a pause. “It’s 30 percent off,” she says, just before the lunch-hour rush.

“I know,” Ms. Latter says, “but can you scan it just to make sure?” Under her breath, she mumbles, “So helpful.” Downstairs in the jewelry department, Ms. Latter tries to price the one 18-inch silver necklace left, but there is no tag. “Do I have to look it up now?” moans the employee behind the counter. Ms. Latter watches her wait on several customers, then asks again: “Could you find it?” The harried saleswoman throws on the counter a thick notebook with a dizzying array of jewelry sketches. Ms. Latter finally locates a silver weave that

looks about right.

When the exact item can’t be found, price-takers must substitute. That can be difficult. Consider a haircut: If the stylist leaves, his fill-in must have about the same experience; a newer stylist, for example, might charge less. This frigid

winter afternoon, Ms. Latter needs to substitute a coat because clothing items rarely remain on the racks for more than a couple months. It must be a lightweight swing coat of less than half wool. After digging through heavy winter wear, trying to locate tags in three departments on two floors, she gives up. It is off season anyway, so she will have to wait months to choose a substitute.

Making it harder for price detectives to grasp the true cost of living is that the master list of 207 categories they price—called the market basket—is updated only once every ten years. Cellular phones? Too new to be priced because they don’t fit into any of the categories set up in the 1980s. They probably will be included when the new categories arrive [next year].

Some changes within these categories are made every five years. So within “new cars,” for example, if domestic autos overtake imports in a big way, price-takers might examine more Fords and fewer Toyotas. But that doesn’t happen often enough, critics say. Ms. Latter, a city-dwelling Generation X’er, continually must price “Always Twenty-One” girdles, yet ignore the new, popular WonderBras behind her. . . .

Ms. Latter’s colleague in suburban Chicago, Sheila Ward, must ignore the hoopla over Tickle Me Elmo and instead price a GI Joe Extreme doll with “painted, molded hair.” Reliance on outdated goods, says Mrs. Ward, “would be one of the criticisms of us.” She recalls a music store owner who became frustrated because she kept seeking prices on a guitar he could never imagine playing— much less selling. He finally threw her out of his shop, screaming, “The damned government! Is this what I’m paying taxes for?”

Price-takers can’t do much about these problems. What they can do is interrogate. At a simple restaurant, Mrs. Ward asks if food portions have changed. The owner says they haven’t. But she remembers that the price of bacon has been climbing, and asks again about his BLT. Suddenly, he recalls that he has cut the number of bacon slices from three to two. And that is a very different sandwich.

SOURCE: The Wall Street Journal, January 16, 1997, p. A1.

Figure 23-2

TWO MEASURES OF INFLATION.

This figure shows the inflation rate—the percentage change in the level of prices—as measured by the GDP deflator and the consumer price index using annual data since 1965. Notice that the two measures of inflation generally move together.

SOURCE: U.S. Department of Labor; U.S.

Department of Commerce.

Percent per Year

15

CPI

10

CASE STUDY MR. INDEX GOES TO HOLLYWOOD

What was the most popular movie of all time? The answer might surprise you. Movie popularity is usually gauged by box office receipts. By that measure, Titanic is the No. 1 movie of all time, followed by Star Wars, Star Wars: The Phantom Menace, and ET. But this ranking ignores an obvious but important fact: Prices, including the price of movie tickets, have been rising over time. When we correct box office receipts for the effects of inflation, the story is very

different.

Table 23-2 shows the top ten movies of all time, ranked by inflationadjusted box office receipts. The No. 1 movie is Gone with the Wind, which was released in 1939 and is well ahead of Titanic. In the 1930s, before everyone had televisions in their homes, about 90 million Americans went to the cinema each week, compared to about 25 million today. But the movies from that era rarely show up in popularity rankings because ticket prices were only a quarter. Scarlett and Rhett fare a lot better once we correct for the effects of inflation.

INDEXATION

“FRANKLY, MY DEAR, I DON’T CARE MUCH

FOR THE EFFECTS OF INFLATION.”

Table 23-2

THE MOST POPULAR MOVIES OF

ALL TIME, INFLATION ADJUSTED

SOURCE: The Movie Times, online Web site (www.the-movie-times.com).

For example, many long-term contracts between firms and unions include partial or complete indexation of the wage to the consumer price index. Such a provision is called a cost-of-living allowance, or COLA. A COLA automatically raises the wage when the consumer price index rises.

Indexation is also a feature of many laws. Social Security benefits, for example, are adjusted every year to compensate the elderly for increases in prices. The brackets of the federal income tax—the income levels at which the tax rates change—are also indexed for inflation. There are, however, many ways in which the tax system is not indexed for inflation, even when perhaps it should be. We discuss these issues more fully when we discuss the costs of inflation later in this book.

REAL AND NOMINAL INTEREST RATES

Correcting economic variables for the effects of inflation is particularly important, and somewhat tricky, when we look at data on interest rates. When you deposit your savings in a bank account, you will earn interest on your deposit. Conversely, when you borrow from a bank to pay your tuition, you will pay interest on your student loan. Interest represents a payment in the future for a transfer of money in the past. As a result, interest rates always involve comparing amounts of money at different points in time. To fully understand interest rates, we need to know how to correct for the effects of inflation.

Let’s consider an example. Suppose that Sally Saver deposits $1,000 in a bank account that pays an annual interest rate of 10 percent. After a year passes, Sally has accumulated $100 in interest. Sally then withdraws her $1,100. Is Sally $100 richer than she was when she made the deposit a year earlier?

The answer depends on what we mean by “richer.” Sally does have $100 more than she had before. In other words, the number of dollars has risen by 10 percent. But if prices have risen at the same time, each dollar now buys less than it did a year ago. Thus, her purchasing power has not risen by 10 percent. If the inflation

Interest Rates (percent per year)

15

10 Nominal interest rate

5

0

Real interest rate

Figure 23-3

REAL AND NOMINAL

INTEREST RATES. This figure shows nominal and real interest rates using annual data since 1965. The nominal interest rate is the rate on a three-month Treasury bill. The real interest rate is the nominal interest rate minus the inflation rate as measured by the consumer price index. Notice that nominal and real interest rates often do not move together.

SOURCE: U.S. Department of Labor;

U.S. Department of Treasury.

rate was 4 percent, then the amount of goods she can buy has increased by only 6 percent. And if the inflation rate was 15 percent, then the price of goods has increased proportionately more than the number of dollars in her account. In that case, Sally’s purchasing power has actually fallen by 5 percent.

The interest rate that the bank pays is called the nominal interest rate, and the interest rate corrected for inflation is called the real interest rate. We can write the relationship among the nominal interest rate, the real interest rate, and inflation as follows:

Real interest rate Nominal interest rate Inflation rate.

The real interest rate is the difference between the nominal interest rate and the rate of inflation. The nominal interest rate tells you how fast the number of dollars in your bank account rises over time. The real interest rate tells you how fast the purchasing power of your bank account rises over time.

Figure 23-3 shows real and nominal interest rates since 1965. The nominal interest rate is the interest rate on three-month Treasury bills. The real interest rate is computed by subtracting inflation—the percentage change in the consumer price index—from this nominal interest rate.

You can see that real and nominal interest rates do not always move together. For example, in the late 1970s, nominal interest rates were high. But because inflation was very high, real interest rates were low. Indeed, in some years, real interest rates were negative, for inflation eroded people’s savings more quickly than nominal interest payments increased them. By contrast, in the late 1990s, nominal interest rates were low. But because inflation was also low, real interest rates were relatively high. In the coming chapters, when we study the causes and effects of

nominal interest rate

the interest rate as usually reported without a correction for the effects of inflation

real interest rate

the interest rate corrected for the effects of inflation