Ten Principles of Economics 2

In this chapter,
look for the answers to these questions:
What are economists’ two roles? How do they differ?
What are models? How do economists use them?
What are the elements of the Circular-Flow Diagram? What concepts does the diagram illustrate?
How is the Production Possibilities Frontier related
to opportunity cost? What other concepts does it illustrate?
What is the difference between microeconomics and macroeconomics? Between positive and normative?

THINKING LIKE AN ECONOMIST
The Economist as Scientist
Economists play two roles:
1. Scientists: try to explain the world
2. Policy advisors: try to improve it
In the first, economists employ the
scientific method,
the dispassionate development and testing of theories about how the world works.

THINKING LIKE AN ECONOMIST
Assumptions & Models
Assumptions simplify the complex world,
make it easier to understand.
Example: To study international trade,
assume two countries and two goods.
Unrealistic, but simple to learn and
gives useful insights about the real world.
Model: a highly simplified representation of
a more complicated reality.
Economists use models to study economic issues.

THINKING LIKE AN ECONOMIST
Some Familiar Models
A road map

THINKING LIKE AN ECONOMIST
Some Familiar Models
A model of human
anatomy from high school biology class

THINKING LIKE AN ECONOMIST
Some Familiar Models
A model airplane

THINKING LIKE AN ECONOMIST
Some Familiar Models
The model teeth at the dentist’s office

THINKING LIKE AN ECONOMIST
Our First Model:
The Circular-Flow Diagram
The Circular-Flow Diagram: a visual model of the economy, shows how dollars flow through markets among households and firms
Two types of “actors”:
households
firms
Two markets:
the market for goods and services
the market for “factors of production”

THINKING LIKE AN ECONOMIST
Factors of Production
Factors of production: the resources the economy uses to produce goods & services, including
labor
land
capital (buildings & machines used in production)
Entrepreneurship

THINKING LIKE AN ECONOMIST
FIGURE 1: The Circular-Flow Diagram
Households:
Own the factors of production, sell/rent them to firms for income
Buy and consume goods & services
Firms:
Buy/hire factors of production,
use them to produce goods and services
Sell goods & services

THINKING LIKE AN ECONOMIST
FIGURE 1: The Circular-Flow Diagram

THINKING LIKE AN ECONOMIST
Our Second Model:
The Production Possibilities Frontier
The Production Possibilities Frontier (PPF):
a graph that shows the combinations of
two goods the economy can possibly produce given the available resources and the available technology
Example:
Two goods: computers and wheat
One resource: labor (measured in hours)
Economy has 50,000 labor hours per month available for production.

PPF Example
Producing one computer requires 100 hours labor.
Producing one ton of wheat requires 10 hours labor.

THINKING LIKE AN ECONOMIST
A
B
C
D
E
PPF Example

A. On the graph, find the point that represents
(100 computers, 3000 tons of wheat), label it F.
Would it be possible for the economy to produce this combination of the two goods?
Why or why not?
B. Next, find the point that represents
(300 computers, 3500 tons of wheat), label it G. Would it be possible for the economy to produce this combination of the two goods?
A C T I V E L E A R N I N G 1
Points off the PPF

A C T I V E L E A R N I N G 1
Answers
Point F:
100 computers, 3000 tons wheat
Point F requires 40,000 hours
of labor.
Possible but
not efficient: could get more
of either good
w/o sacrificing any of the other.

A C T I V E L E A R N I N G 1
Answers
Point G:
300 computers, 3500 tons wheat
Point G requires 65,000 hours
of labor.
Not possible because
economy
only has
50,000 hours.

THINKING LIKE AN ECONOMIST
The PPF: What We Know So Far
Points on the PPF (like A – E)
possible
efficient: all resources are fully utilized
Points under the PPF (like F)
possible
not efficient: some resources underutilized
(e.g., workers unemployed, factories idle)
Points above the PPF (like G)
not possible

THINKING LIKE AN ECONOMIST
The PPF and Opportunity Cost
Recall: The opportunity cost of an item
is what must be given up to obtain that item.
Moving along a PPF involves shifting resources (e.g., labor) from the production of one good to the other.
Society faces a tradeoff: Getting more of one good requires sacrificing some of the other.
The slope of the PPF tells you the opportunity cost of one good in terms of the other.

THINKING LIKE AN ECONOMIST
The PPF and Opportunity Cost
The slope of a line equals the
“rise over the run,” the amount the line rises when you move to the right by one unit.
–1000
100
= –10
Here, the opportunity cost of a computer is
10 tons of wheat.

A C T I V E L E A R N I N G 2
PPF and Opportunity Cost
In which country is the opportunity cost of cloth lower?
FRANCE
ENGLAND

A C T I V E L E A R N I N G 2
Answers
FRANCE
ENGLAND
England, because its PPF is not as steep as France’s.

THINKING LIKE AN ECONOMIST
Economic Growth and the PPF
With additional resources or an improvement in technology,
the economy can produce more computers,
more wheat,
or any combination in between.
Economic growth shifts the PPF outward.

THINKING LIKE AN ECONOMIST
The Shape of the PPF
The PPF could be a straight line, or bow-shaped
Depends on what happens to opportunity cost
as economy shifts resources from one industry
to the other.
If opp. cost remains constant,
PPF is a straight line.
(In the previous example, opp. cost of a computer was always 10 tons of wheat.)
If opp. cost of a good rises as the economy produces more of the good, PPF is bow-shaped.

THINKING LIKE AN ECONOMIST
Why the PPF Might Be Bow-Shaped
As the economy shifts resources
from beer to mountain bikes:
PPF becomes steeper
opp. cost of mountain bikes increases

THINKING LIKE AN ECONOMIST
A
Why the PPF Might Be Bow-Shaped
At point A,
most workers are
producing beer,
even those that
are better suited
to building bikes.
So, do not have to
give up much beer to get more bikes.
Mountain Bikes
Beer
At A, opp. cost of mtn bikes is low.

THINKING LIKE AN ECONOMIST
B
Why the PPF Might Be Bow-Shaped
At B, most workers are producing bikes.
The few left in beer are the best brewers.
Producing more bikes would require shifting some of the best brewers away from beer production,
would cause a big drop in beer output.
Mountain Bikes
Beer
At B, opp. cost of mtn bikes
is high.

THINKING LIKE AN ECONOMIST
Why the PPF Might Be Bow-Shaped
So, PPF is bow-shaped when different workers have different skills, different opportunity costs of producing one good in terms of the other.
The PPF would also be bow-shaped when there is some other resource, or mix of resources with varying opportunity costs
(E.g., different types of land suited for
different uses).

THINKING LIKE AN ECONOMIST
The PPF: A Summary
The PPF shows all combinations of two goods that an economy can possibly produce,
given its resources and technology.
The PPF illustrates the concepts of
tradeoff and opportunity cost,
efficiency and inefficiency,
unemployment, and economic growth.
A bow-shaped PPF illustrates the concept of increasing opportunity cost.

THINKING LIKE AN ECONOMIST
Microeconomics and Macroeconomics
Microeconomics is the study of how households and firms make decisions and how they interact in markets.
Macroeconomics is the study of economy-wide phenomena, including inflation, unemployment, and economic growth.
These two branches of economics are closely intertwined, yet distinct – they address different questions.

The Economist as Policy Advisor
As scientists, economists make
positive statements,
which attempt to describe the world as it is.
As policy advisors, economists make
normative statements,
which attempt to prescribe how the world should be.
Positive statements can be confirmed or refuted,
normative statements cannot.
Govt employs many economists for policy advice. E.g., the U.S. President has a Council of Economic Advisors, which the author of this textbook chaired from 2003 to 2005.

A C T I V E L E A R N I N G 3
Identifying positive vs. normative
Which of these statements are “positive” and which are “normative”? How can you tell the difference?
a. Prices rise when the government increases the quantity of money.
b. The government should print less money.
c. A tax cut is needed to stimulate the economy.
d. An increase in the price of burritos will cause an increase in consumer demand for video rentals.

A C T I V E L E A R N I N G 3
Answers
a. Prices rise when the government increases the quantity of money.
Positive – describes a relationship, could use data to confirm or refute.
b. The government should print less money.
Normative – this is a value judgment, cannot be confirmed or refuted.

A C T I V E L E A R N I N G 3
Answers
c. A tax cut is needed to stimulate the economy.
Normative – another value judgment.
d. An increase in the price of burritos will cause an increase in consumer demand for video rentals.
Positive – describes a relationship.
Note that a statement need not be true to be positive.

THINKING LIKE AN ECONOMIST
Why Economists Disagree
Economists often give conflicting policy advice.
They sometimes disagree about the validity of alternative positive theories about the world.
They may have different values and, therefore, different normative views about what policy should try to accomplish.
Yet, there are many propositions about which most economists agree.

THINKING LIKE AN ECONOMIST
Propositions about Which Most
Economists Agree (and % who agree)
A ceiling on rents reduces the quantity and quality of housing available. (93%)
Tariffs and import quotas usually reduce general economic welfare. (93%)
The United States should not restrict employers from outsourcing work to foreign countries. (90%)
The United States should eliminate agriculture subsidies. (85%)
continued…

THINKING LIKE AN ECONOMIST
Propositions about Which Most
Economists Agree (and % agreeing)
The gap between Social Security funds and expenditures will become unsustainably large
within the next fifty years if current policies remain unchanged. (85%)
A large federal budget deficit has an adverse effect on the economy. (83%)
A minimum wage increases unemployment among young and unskilled workers. (79%)
Effluent taxes and marketable pollution permits represent a better approach to pollution control
than imposition of pollution ceilings. (78%)

FYI: Who Studies Economics?
Ronald Reagan, President of the United States
Barbara Boxer, U.S. Senator
Sandra Day-O’Connor, Former Supreme Court Justice
Anthony Zinni, Former General, U.S. Marine Corps
Kofi Annan, Former Secretary General, United Nations
Meg Witman, Chief Executive Officer, eBay
Steve Ballmer, Chief Executive Officer, Microsoft
Arnold Schwarzenegger, Governor of California, Actor
Ben Stein, Political Speechwriter, Actor, Game Show Host
Mick Jagger, Singer for the Rolling Stones
John Elway, NFL Quarterback
Tiger Woods, Golfer
Diane von Furstenburg, Fashion Designer