2 THINKING LIKE AN ECONOMIST
WHAT’S NEW IN THE FIFTH EDITION:
There are two new In the News features: “Go for It on Fourth Down, Coach?” and “Environmental
Economics.” New propositions have been added to the table showing “Propositions about which Economists Agree.”
By the end of this chapter, students should understand:
？;how economists apply the methods of science.
？;how assumptions and models can shed light on the world.
？;two simple models—the circular flow and the production possibilities frontier.
？;the difference between microeconomics and macroeconomics.
？;the difference between positive and normative statements.
？;the role of economists in making policy.
？;why economists sometimes disagree with one another.
CONTEXT AND PURPOSE:
Chapter 2 is the second chapter in a three chapter section that serves as the introduction of the text. Chapter 1 introduced ten principles of economics that will be revisited throughout the text. Chapter 2 develops how economists approach problems while Chapter 3 will explain how individuals and countries gain from trade.
The purpose of Chapter 2 is to familiarize students with how economists approach economic problems. With practice, they will learn how to approach similar problems in this dispassionate systematic way. They will see how economists employ the scientific method, the role of assumptions in model building, and the application of two specific economic models. Students will also learn the important distinction between two roles economists can play: as scientists when we try to explain the economic world and as policymakers when we try to improve it.
16 ； Chapter 2/Thinking Like an Economist
？;Economists try to address their subject with a scientist’s objectivity. Like all scientists, they make
appropriate assumptions and build simplified models in order to understand the world around them.
Two simple economic models are the circular-flow diagram and the production possibilities frontier.
？;The field of economics is divided into two subfields: microeconomics and macroeconomics.
Microeconomists study decisionmaking by households and firms and the interaction among
households and firms in the marketplace. Macroeconomists study the forces and trends that affect
the economy as a whole.
？;A positive statement is an assertion about how the world is. A normative statement is an assertion
about how the world ought to be. When economists make normative statements, they are acting
more as policy advisers than scientists.
？;Economists who advise policymakers offer conflicting advice either because of differences in scientific
judgments or because of differences in values. At other times, economists are united in the advice
they offer, but policymakers may choose to ignore it.
I. The Economist as Scientist
A. Economists Follow the Scientific Method.
1. Observations help us to develop theory.
2. Data can be collected and analyzed to evaluate theories.
3. Using data to evaluate theories is more difficult in economics than in physical science
because economists are unable to generate their own data and must make do with whatever
data are available.
4. Thus, economists pay close attention to the natural experiments offered by history.
B. Assumptions Make the World Easier to Understand.
1. Example: to understand international trade, it may be helpful to start out assuming that
there are only two countries in the world producing only two goods. Once we understand
how trade would work between these two countries, we can extend our analysis to a greater
number of countries and goods.
2. One important role of a scientist is to understand which assumptions one should make.
3. Economists often use assumptions that are somewhat unrealistic but will have small effects
on the actual outcome of the answer.
C. Economists Use Economic Models to Explain the World Around Us.
Chapter 2/Thinking Like an Economist ； 17
To illustrate to the class how simple but unrealistic models can be useful, bring a
road map to class. Point out how unrealistic it is. For example, it does not show
where all of the stop signs, gas stations, or restaurants are located. It assumes that
the earth is flat and two-dimensional. But, despite these simplifications, a map
usually helps travelers get from one place to another. Thus, it is a good model.
1. Most economic models are composed of diagrams and equations.
2. The goal of a model is to simplify reality in order to increase our understanding. This is
where the use of assumptions is helpful.
D. Our First Model: The Circular Flow Diagram
1. Definition of circular-flow diagram: a visual model of the economy that shows how
dollars flow through markets among households and firms.
18 ； Chapter 2/Thinking Like an Economist
2. This diagram is a very simple model of the economy. Note that it ignores the roles of
government and international trade.
a. There are two decision makers in the model: households and firms.
b. There are two markets: the market for goods and services and the market of factors of
c. Firms are sellers in the market for goods and services and buyers in the market for
factors of production.
d. Households are buyers in the market for goods and services and sellers in the market for
factors of production.
e. The inner loop represents the flows of inputs and outputs between households and firms.
f. The outer loop represents the flows of dollars between households and firms.
E. Our Second Model: The Production Possibilities Frontier
1. Definition of production possibilities frontier: a graph that shows the combinations
of output that the economy can possibly produce given the available factors of
production and the available production technology.
Spend more time with this model than you think is necessary. Be aware that the
math and graphing skills of many of your students will be limited. It is important for the students to feel confident with this first graphical and mathematical model. Be
deliberate with every point. If you lose them with this model, they may be gone for
the rest of the course.
2. Example: an economy that produces two goods, cars and computers.
a. If all resources are devoted to producing cars, the economy would produce 1,000 cars
and zero computers.
b. If all resources are devoted to producing computers, the economy would produce 3,000
computers and zero cars.
c. More likely, the resources will be divided between the two industries. The feasible
combinations of output are shown on the production possibilities frontier.
Chapter 2/Thinking Like an Economist ； 19
You may want to include time dimensions for variables . This will help students to
realize that a new production possibilities frontier occurs for each period. Thus, the
axes show the levels of output per period.
ALTERNATIVE CLASSROOM EXAMPLE:
A small country produces two goods: corn (measured in bushels) and trucks. Points on a
production possibilities frontier can be shown in a table or a graph:
A B C D E
Trucks 0 10 20 30 40
Corn 70 60 45 25 0
The production possibilities frontier should be drawn from the numbers above.
Students should be asked to calculate the opportunity cost of increasing the number of trucks produced by ten:
？;between 0 and 10
？;between 10 and 20
？;between 20 and 30
？;between 30 and 40 Points inside the curve, points on the curve, and points outside of the curve can also be discussed. 3. Because resources are scarce, not every combination of computers and cars is possible. Production at a point outside of the curve (such as C) is not possible given the economy’s
current level of resources and technology.
20 ； Chapter 2/Thinking Like an Economist
It is useful to point out that the production possibilities curve depends on two things:
the availability of resources and the level of technology.
4. Production is efficient at points on the curve (such as A and B). This implies that the
economy is getting all it can from the scarce resources it has available. There is no way to
produce more of one good without producing less of another.
5. Production at a point inside the curve (such as D) is inefficient.
a. This means that the economy is producing less than it can from the resources it has
b. If the source of the inefficiency is eliminated, the economy can increase its production of
6. The production possibilities frontier reveals Principle #1: People face tradeoffs.
a. Suppose the economy is currently producing 600 cars and 2,200 computers.
b. To increase the production of cars to 700, the production of computers must fall to 2,000.
7. Principle #2 is also shown on the production possibilities frontier: The cost of something is
what you give up to get it (opportunity cost).
a. The opportunity cost of increasing the production of cars from 600 to 700 is 200
b. Thus, the opportunity cost of each car is two computers.
8. The opportunity cost of a car depends on the number of cars and computers currently
produced by the economy.
a. The opportunity cost of a car is high when the economy is producing many cars and few
b. The opportunity cost of a car is low when the economy is producing few cars and many
9. Economists generally believe that production possibilities frontiers often have this bowed-out
shape because some resources are better suited to the production of cars than computers
(and vice versa).
Be aware that students often have trouble understanding why opportunity costs rise
as the production of a good increases. You may want to use several specific
examples of resources that are more suited to producing cars than computers (e.g., an experienced mechanic) as well as examples of resources that are more
suited to producing computers than cars (e.g., an experienced computer
Chapter 2/Thinking Like an Economist ； 21
10. The production possibilities frontier can shift if resource availability or technology changes.
Economic growth can be illustrated by an outward shift of the production possibilities frontier.
You may also want to teach students about budget constraints at this time (call them
“consumption possibilities frontiers”). This reinforces the idea of opportunity cost,
and allows them to see how opportunity cost can be measured by the slope. Also, it
will introduce students to the use of a straight-line production possibilities frontier
(which is used in Chapter 3). However, be careful if you choose to do this as
students often find the difference between straight-line and concave production
possibilities frontiers challenging.
ALTERNATIVE CLASSROOM EXAMPLE:
Ivan receives an allowance from his parents of $10 each week. He spends his entire
allowance on two goods: ice cream cones (which cost $1 each) and tickets to the movies (which cost $5 each).
Students should be asked to calculate the opportunity cost of one movie and the opportunity cost of one ice cream cone.
Ivan’s consumption possibilities frontier (budget constraint) can be drawn. It should be noted
that the slope is equal to the opportunity cost and is constant because the opportunity cost is constant.
Ask students what would happen to the consumption possibilities frontier if Ivan’s allowance
changes or if the price of ice cream cones or movies changes.
F. Microeconomics and Macroeconomics
1. Economics is studied on various levels.
a. Definition of microeconomics: the study of how households and firms make
decisions and how they interact in markets.
b. Definition of macroeconomics: the study of economy-wide phenomena,
including inflation, unemployment, and economic growth.
2. Microeconomics and macroeconomics are closely intertwined because changes in the overall
economy arise from the decisions of individual households and firms.
3. Because microeconomics and macroeconomics address different questions, each field has its
own set of models which are often taught in separate courses.
G. FYI: Who Studies Economics?
1. Economics can seem abstract at first, but it is fundamentally very practical and the study of
economics is useful in many different career paths.
22 ； Chapter 2/Thinking Like an Economist
2. This box provides a sample of well-known individuals who majored in economics in college.
II. The Economist as Policy Adviser
A. Positive Versus Normative Analysis
1. Example of a discussion of minimum-wage laws: Polly says, “Minimum-wage laws cause
unemployment.” Norma says, “The government should raise the minimum wage.”
2. Definition of positive statements: claims that attempt to describe the world as it is.
3. Definition of normative statements: claims that attempt to prescribe how the world
4. Positive statements can be evaluated by examining data, while normative statements involve
5. Positive views about how the world works affect normative views about which policies are
Use several examples to illustrate the differences between positive and normative statements and stimulate classroom discussion. Possible examples include the
minimum wage, budget deficits, tobacco taxes, legalization of marijuana, and seat-
Have students bring in newspaper articles and in groups, identify each statement in an editorial paragraph as being a positive or normative statement. Discuss the
difference between straight news stories and editorials and the analogy to economists as scientists and as policy advisers.
6. Much of economics is positive; it tries to explain how the economy works. But those who use
economics often have goals that are normative. They want to understand how to improve
7. In the News: Football Economics
a. Economists often offer advice to policymakers (including football coaches).
b. This is an article from The Washington Post that describes economist David Romer’s
research on the tendency of NFL teams to punt more often than necessary.
B. Economists in Washington
1. Economists are aware that trade-offs are involved in most policy decisions.
2. The president receives advice from the Council of Economic Advisers (created in 1946).
3. Economists are also employed by administrative departments within the various federal
agencies such as the Department of Treasury, the Department of Labor, the Congressional
Budget Office, and the Federal Reserve.
Chapter 2/Thinking Like an Economist ； 23
4. The research and writings of economists can also indirectly affect public policy.
C. Why Economists’ Advice Is Not Always Followed
1. The process by which economic policy is made differs from the idealized policy process
assumed in textbooks.
2. Economists offer crucial input into the policy process, but their advice is only part of the
advice received by policymakers.
III. Why Economists Disagree
A. Differences in Scientific Judgments
1. Economists may disagree about the validity of alternative positive theories or about the size
of the effects of changes in the economy on the behavior of households and firms.
2. Example: some economists feel that a change in the tax code that would eliminate a tax on
income and create a tax on consumption would increase saving in this country. However,
other economists feel that the change in the tax system would have little effect on saving
behavior and therefore do not support the change.
B. Differences in Values
C. Perception versus Reality
1. While it seems as if economists do not agree on much, this is in fact not true. Table 1
contains fourteen propositions that are endorsed by a majority of economists.
Emphasize that there is more agreement among economists than most people think.
The reason for this is probably that the things that are generally agreed upon are
boring to most noneconomists.
2. Almost all economists believe that rent control adversely affects the availability and quality of
3. Most economists also oppose barriers to trade.
IV. In the News: Environmental Economics
A. Some economists are working on ways to help save the planet.
B. This is an article from the Wall Street Journal describing the field of environmental economics.
V. Appendix—Graphing: A Brief Review
24 ； Chapter 2/Thinking Like an Economist
Many instructors may be unaware of how much trouble beginning students have
grasping the most basic graphs. It is important for instructors to make sure that
students are comfortable with these techniques.
When reviewing graphing with the students, it is best to bring students to the board
to be “recorders” of what the other students say as you give a series of instructions
like “Draw a pie chart” or ask questions like “How tall should the bar be if the value is
120 million?” Do not make the student at the board responsible for the answer.
Instead he should be simply recording what the other students say. Students are
often uneasy about graphing at first and need to gain confidence.
A. Graphs of a Single Variable
1. Pie Chart
2. Bar Graph
3. Time-Series Graph
B. Graphs of Two Variables: The Coordinate System
1. Economists are often concerned with relationships between two or more variables.
2. Ordered pairs of numbers can be graphed on a two-dimensional grid.
a. The first number in the ordered pair is the x-coordinate and tells us the horizontal
location of the point.
b. The second number in the ordered pair is the y-coordinate and tells us the vertical
location of the point.
3. The point with both an x-coordinate and y-coordinate of zero is called the origin.
4. Two variables that increase or decrease together have a positive correlation.
5. Two variables that move in opposite directions (one increases when the other decreases)
have a negative correlation.
C. Curves in the Coordinate System
1. Often, economists want to show how one variable affects another, holding all other variables