Measuring a Nation’s Income

 Mankiw Ch. 10

Introduction to Macroeconomics – Dao Hoang Tuan 0

 GDP and Economic Well-Being
 Real GDP per capita is the main indicator of
the average person’s standard of living.
 But GDP is not a perfect measure of
well-being.

MEASURING A NATION’S INCOME 1

 GDP Does Not Value:
 the quality of the environment
 leisure time
 non-market activity, such as the child care
a parent provides his or her child at home
 an equitable distribution of income

MEASURING A NATION’S INCOME 2

 Then Why Do We Care About GDP?
 Having a large GDP enables a country to afford
better schools, a cleaner environment,
health care, etc.
 Many indicators of the quality of life are
positively correlated with GDP. For example…

MEASURING A NATION’S INCOME 3

 GDP and Life Expectancy in 12 countries

Indonesia
Japan
China
Life expectancy (years)

U.S.
Mexico Germany
Brazil
Pakistan
Russia
India
Bangladesh

Nigeria

Real GDP per capita 4

 GDP and Literacy in 12 countries
China Russia U.S.
Germany Japan
Mexico
(% of population)

Brazil
Adult Literacy

Indonesia

Nigeria

India

Pakistan

Bangladesh

Real GDP per capita 5

 GDP and Internet Usage in 12 countries

Japan
U.S.
(% of population)
Internet Usage

Germany

Brazil
Indonesia
Mexico
Pakista
Russia
n
China
Nigeria India

Bangladesh Real GDP per capita 6

CHAPTER SUMMARY

 Gross Domestic Product (GDP) measures a

country’s total income and expenditure.
 The four spending components of GDP include:
Consumption, Investment, Government Purchases,
and Net Exports.
 Nominal GDP is measured using current prices.
Real GDP is measured using the prices of a
constant base year and is corrected for inflation.
 GDP is the main indicator of a country’s economic
well-being, even though it is not perfect. 7
 Measuring the Cost of Living

 Mankiw Ch. 11

Introduction to Macroeconomics – Dao Hoang Tuan 8

In this chapter,
look for the answers to these questions:
 What is the Consumer Price Index (CPI)?
How is it calculated? What’s it used for?
 What are the problems with the CPI? How serious
are they?
 How does the CPI differ from the GDP deflator?
 How can we use the CPI to compare dollar
amounts from different years? Why would we want
to do this, anyway?
 How can we correct interest rates for inflation?
9
 The Consumer Price Index (CPI)
 measures the typical consumer’s cost of living
 the basis of cost of living adjustments (COLAs) in
many contracts and in Social Security

Introduction to Macroeconomics – Dao Hoang Tuan 10

 How the CPI Is Calculated
1. Fix the “basket.”
The Bureau of Labor Statistics (BLS) surveys
consumers to determine what’s in the typical
consumer’s “shopping basket.”
2. Find the prices.
The BLS collects data on the prices of all the
goods in the basket.
3. Compute the basket’s cost.
Use the prices to compute the total cost of the
basket.

Introduction to Macroeconomics – Dao Hoang Tuan 11

 How the CPI Is Calculated
4. Choose a base year and compute the index.
The CPI in any year equals
cost of basket in current year
100 x
cost of basket in base year

5. Compute the inflation rate.

The percentage change in the CPI from the
preceding period.

Inflation CPI this year – CPI last year

= x 100%
rate CPI last year
Introduction to Macroeconomics – Dao Hoang Tuan 12
EXAMPLE basket: {4 pizzas, 10 lattes}

price of price of
year cost of basket
pizza latte
2007 $10 $2.00 $10 x 4 + $2 x 10 = $60
2008 $11 $2.50 $11 x 4 + $2.5 x 10 = $69
2009 $12 $3.00 $12 x 4 + $3 x 10 = $78

Compute CPI in each year using 2007 base year:

Inflation rate:
2007: 100 x ($60/$60) = 100 115 – 100
15% = x 100%
100
2008: 100 x ($69/$60) = 115
130 – 115
13% = x 100%
2009: 100 x ($78/$60) = 130 115

Introduction to Macroeconomics – Dao Hoang Tuan 13

ACTIVE LEARNING 1
Calculate the CPI
price price of
CPI basket: of beef chicken
{10 lbs beef,
2004 $4 $4
20 lbs chicken}
2005 $5 $5
The CPI basket cost $120
in 2004, the base year. 2006 $9 $6

A. Compute the CPI in 2005.

B. What was the CPI inflation rate from 2005-2006?

14
ACTIVE LEARNING 1
Answers
price price of
CPI basket: of beef chicken
{10 lbs beef,
2004 $4 $4
20 lbs chicken}
2005 $5 $5
The CPI basket cost $120
in 2004, the base year. 2006 $9 $6

A. Compute the CPI in 2005:

Cost of CPI basket in 2005
= ($5 x 10) + ($5 x 20) = $150

CPI in 2005 = 100 x ($150/$120) = 125

15
ACTIVE LEARNING 1
Answers
price price of
CPI basket: of beef chicken
{10 lbs beef,
2004 $4 $4
20 lbs chicken}
2005 $5 $5
The CPI basket cost $120
in 2004, the base year. 2006 $9 $6

B. What was the inflation rate from 2005-2006?

Cost of CPI basket in 2006
= ($9 x 10) + ($6 x 20) = $210
CPI in 2006 = 100 x ($210/$120) = 175
CPI inflation rate = (175 – 125)/125 = 40%
16
 What’s in the CPI’s Basket?
4% 3% Housing
6%
Transportation
6%
Food & Beverages
6% 43%
Medical care

Recreation

Education and
15%
communication
Apparel

17% Other

Introduction to Macroeconomics – Dao Hoang Tuan 17

ACTIVE LEARNING 2
Substitution bias
CPI basket:
cost of CPI
{10# beef, beef chicken
basket
20# chicken}
2004 $4 $4 $120
2004-5:
2005 $5 $5 $150
Households
bought CPI basket. 2006 $9 $6 $210

2006: Households bought {5 lbs beef, 25 lbs chicken}.

A. Compute cost of the 2006 household basket.

B. Compute % increase in cost of household basket
over 2005-6, compare to CPI inflation rate.
18
ACTIVE LEARNING 2
Answers
CPI basket: cost of CPI
{10# beef, beef chicken
basket
20# chicken}
2004 $4 $4 $120
Household
basket in 2006: 2005 $5 $5 $150
{5# beef, 2006 $9 $6 $210
25# chicken}

A. Compute cost of the 2006 household basket.

($9 x 5) + ($6 x 25) = $195

19
ACTIVE LEARNING 2
Answers
CPI basket: cost of CPI
{10# beef, beef chicken
basket
20# chicken}
2004 $4 $4 $120
Household
basket in 2006: 2005 $5 $5 $150
{5# beef, 2006 $9 $6 $210
25# chicken}
B. Compute % increase in cost of household basket
over 2005-6, compare to CPI inflation rate.
Rate of increase: ($195 – $150)/$150 = 30%
CPI inflation rate from previous problem = 40%
20
 Problems with the CPI:
Substitution Bias
 Over time, some prices rise faster than others.
 Consumers substitute toward goods that become
relatively cheaper.
 The CPI misses this substitution because it uses
a fixed basket of goods.
 Thus, the CPI overstates increases in the cost of
living.

Introduction to Macroeconomics – Dao Hoang Tuan 21

 Problems with the CPI:
Introduction of New Goods
 The introduction of new goods increases variety,
allows consumers to find products that more
closely meet their needs.
 In effect, dollars become more valuable.
 The CPI misses this effect because it uses a
fixed basket of goods.
 Thus, the CPI overstates increases in the cost of
living.

Introduction to Macroeconomics – Dao Hoang Tuan 22

 Problems with the CPI:
Unmeasured Quality Change
 Improvements in the quality of goods in the
basket increase the value of each dollar.
 The BLS tries to account for quality changes
but probably misses some, as quality is hard to
measure.
 Thus, the CPI overstates increases in the cost of
living.

Introduction to Macroeconomics – Dao Hoang Tuan 23

THE MARKET FORCES OF SUPPLY AND DEMAND 24
THE MARKET FORCES OF SUPPLY AND DEMAND 25
THE MARKET FORCES OF SUPPLY AND DEMAND 26
THE MARKET FORCES OF SUPPLY AND DEMAND 27
THE MARKET FORCES OF SUPPLY AND DEMAND 28
THE MARKET FORCES OF SUPPLY AND DEMAND 29
 Problems with the CPI
 Each of these problems causes the CPI to
overstate cost of living increases.
 The CPI probably still overstates inflation
by about 0.5 percent per year.

Introduction to Macroeconomics – Dao Hoang Tuan 30

 Two Measures of Inflation, 1950-2007
Percent
15
per Year

10

-5
1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005
CPI GDP deflator

Introduction to Macroeconomics – Dao Hoang Tuan 31

 Contrasting the CPI and GDP Deflator
Imported consumer goods:
 included in CPI
 excluded from GDP deflator
Capital goods:
 excluded from CPI
 included in GDP deflator
The basket:
(if produced domestically)
 CPI uses fixed basket
 GDP deflator uses basket of
currently produced goods & services
This matters if different prices are
changing by different amounts.

Introduction to Macroeconomics – Dao Hoang Tuan 32

ACTIVE LEARNING 3
CPI vs. GDP deflator
In each scenario, determine the effects on the
CPI and the GDP deflator.
A. Starbucks raises the price of Frappuccinos.
B. Caterpillar raises the price of the industrial
tractors it manufactures at its Illinois factory.
C. Armani raises the price of the Italian jeans it
sells in the U.S.

33
ACTIVE LEARNING 3
Answers
A. Starbucks raises the price of Frappuccinos.
The CPI and GDP deflator both rise.
B. Caterpillar raises the price of the industrial
tractors it manufactures at its Illinois factory.
The GDP deflator rises, the CPI does not.
C. Armani raises the price of the Italian jeans it
sells in the U.S.
The CPI rises, the GDP deflator does not.

34
 Correcting Variables for Inflation:
Comparing Dollar Figures from Different Times
 Inflation makes it harder to compare dollar
amounts from different times.
 Example: the minimum wage
 $1.15 in Dec 1964
 $5.85 in Dec 2007
 Did min wage have more purchasing power in
Dec 1964 or Dec 2007?
 To compare, use CPI to convert 1964 figure into
“today’s dollars”…

Introduction to Macroeconomics – Dao Hoang Tuan 35

 Correcting Variables for Inflation:
Comparing Dollar Figures from Different Times
Amount Amount Price level today
in today’s = in year T x
dollars dollars Price level in year T

 In our example,
 year T = 12/1964, “today” = 12/2007
 Min wage = $1.15 in year T
 CPI = 31.3 in year T, CPI = 211.7 today
The minimum wage 211.7
in 1964 was $7.78 $7.78 = $1.15 x
31.3
in today’s (2007) dollars.
Introduction to Macroeconomics – Dao Hoang Tuan 36
 Correcting Variables for Inflation:
Comparing Dollar Figures from Different Times
 Researchers, business analysts and policymakers
often use this technique to convert a time series of
current-dollar (nominal) figures into constant-dollar
(real) figures.
 They can then see how a variable has changed
over time after correcting for inflation.
 Example: the minimum wage, from Jan 1950 to
Dec 2007…

Introduction to Macroeconomics – Dao Hoang Tuan 37

 The U.S. Minimum Wage in Current Dollars
and Today’s Dollars, 1950-2007
$9

$8 2007 dollars
$ per hour

$7

$6

$5

$4

$3

$2 current dollars
$1

$0
1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005
ACTIVE LEARNING 4
Converting to “today’s dollars”
Annual tuition and fees, average of all public four-
year colleges & universities in the U.S.
 1986-87: $1,414 (1986 CPI = 109.6)
 2006-07: $5,834 (2006 CPI = 203.8)
After adjusting for inflation, did students pay more for
college in 1986 or in 2006? Convert the 1986 figure
to 2006 dollars and compare.

39
ACTIVE LEARNING 4
Answers
Annual tuition and fees, average of all public four-
year colleges & universities in the U.S.
 1986-87: $1,414 (1986 CPI = 109.6)
 2006-07: $5,834 (2006 CPI = 203.8)
Solution
Convert 1986 figure into “today’s dollars”
$1,414 x (203.8/109.6) = $2,629
Even after correcting for inflation, tuition and fees
were much lower in 1986 than in 2006!
40
 Correcting Variables for Inflation:
Real vs. Nominal Interest Rates
The nominal interest rate:
 the interest rate not corrected for inflation
 the rate of growth in the dollar value of a
deposit or debt
The real interest rate:
 corrected for inflation
 the rate of growth in the purchasing power of a
deposit or debt
Real interest rate
= (nominal interest rate) – (inflation rate)
Introduction to Macroeconomics – Dao Hoang Tuan 41
 Correcting Variables for Inflation:
Real vs. Nominal Interest Rates
Example:
 Deposit $1,000 for one year.
 Nominal interest rate is 9%.
 During that year, inflation is 3.5%.
 Real interest rate
= Nominal interest rate – Inflation
= 9.0% – 3.5% = 5.5%
 The purchasing power of the $1000 deposit
has grown 5.5%.

Introduction to Macroeconomics – Dao Hoang Tuan 42

 Real and Nominal Interest Rates in the U.S.,
1950-2007

15
(percent per year)

10
Interest Rates

-5

-10
1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005

Nominal interest rate Real interest rate

Introduction to Macroeconomics – Dao Hoang Tuan 43

CHAPTER SUMMARY

 The Consumer Price Index is a measure of the

cost of living. The CPI tracks the cost of the typical
consumer’s “basket” of goods & services.
 The CPI is used to make Cost of Living
Adjustments and to correct economic variables for
the effects of inflation.
 The real interest rate is corrected for inflation
and is computed by subtracting the inflation rate
from the nominal interest rate.
44
 Keywords
 Intangible: Vô hình
 Inventories: Hàng tồn kho
 Nominal GDP: GDP danh nghĩa
 Real GDP: GDP thực
 Consumers: Người tiêu dùng
 Basket: Rổ (hàng hóa)
 Lbs: Pounds (=0.453592 kilogram)
 Nominal interest rate: Lãi suất danh nghĩa
 Real interest rate: Lãi suất thực
 MSRP (manufacturer's suggested retail price): Mức giá
bán lẻ khuyến nghị của nhà sản xuất

Introduction to Macroeconomics – Dao Hoang Tuan 45