1. Lecture 1. What is Economics?
Economics, Scarcity and Choices
Microeconomics and Macroeconomics
Positive Economics and Normative Economics
Why study Economics
The method of Economics

2. Economics, Scarcity, and Choice
A good definition of economics
Study of choice under conditions of scarcity
Scarcity
Situation in which the amount of something available is insufficient to satisfy the desire for it (Human beings have unlimited wants and needs in general)

3. Scarcity and Individual Choice
Two basic limitations for individuals
Scarce time
Scarce spending power
Limitations force each of us to make choices
The scarcity of resources—and the choices it forces us to make—is the source of all of the problems studied in economics
Examples: Dating & Getting A in this class

4. Microeconomics
Study of behavior of individual households, firms, and governments
Choices they make
Interaction in specific markets
Focuses on individual parts of an economy, rather than the whole
Examples:
How many management trainee jobs will open up for college graduates?
How would U.S. phone companies be affected by a tax on imported cell phones?

5. Macroeconomics Study of the economy as a whole
Focuses on big picture and ignores fine details
Examples:
Instead of focusing on the production of carrots, it looks at GDP.
Instead of focusing on the employment of management trainees, it considers total employment (or unemployment rate) in the economy.
Instead of asking why credit card loans carry high interest rate than home mortgage loans, it asks what makes interest rates in general rise or fall.

6. Why Economists Disagree
Two economists asked whether the States should eliminate all government-imposed barriers to trading with the rest of the world. The first economist says, ‘Yes.’ but the other says, ‘No’.
The two economists may disagree about what will happen if trade barriers were eliminated. In this case, the disagreement is positive.
Both economists might agree that opening up international trade would benefit most Americans, but harm some of them.
The first economist might put more emphasis on benefits to the overall economy
The second economist might put more emphasis on preventing harm to a particular group.
In this case, the disagreement is normative.

7. Positive Economics Study of how economy works
Accuracy of positive statements can be tested and quantified.
Examples: An decrease in the personal income tax will increase the growth rate of the economy.

8. Normative Economics Use Value Judgment to study what should be
Normative statements cannot be proved or disproved by the facts alone
Example: The goal of any country’s economic policy should be to increase the well-being of its poorest, most vulnerable citizens.

9. The Methods of Economics
Model. What is a model?
A Model is an Abstract representation of reality.
A Model should be as simple as possible to accomplish its purpose.
A model should contain the right amount of details.

10. Drive from Ames to Chicago

11. Drive from Chicago O’Hare International Airport to Hilton Tower Chicago

12. Assumptions and Conclusions
Simplifying assumptions
Way of making a model simpler without affecting any of its important conclusions
Example: When we study the behavior of consumers, we assume that there are only two goods to choose from.
Critical assumptions
Affect conclusions of a model in important ways
Example: When we study the behavior of business firms, we assume that firms try to earn the highest possible profit.

13. Why Study Economics To Understand the World Better
To Achieve Social Change
To Help prepare for Other Careers
To become an Economist
Median annual wage and salary earnings of economists were $72,780 in May Check out

14. How to Study Economics
Economics must be studied actively, not passively
What does active studying mean?
Closing the book periodically and reproducing what you have learned
Reading with a pencil in your hand and a blank sheet of paper in front of you
Listing the steps in each logical argument
Retracing the cause-and-effect steps in each model
Drawing the graphs that represent the model
Thinking about the basic principles of economics and how they relate to what you are learning

15. Appendix: Tables and Graphs
Table A.1 Advertising and Sales at Len & Harry’s

16. Appendix: Tables and Graphs
Advertising ($1,000 per Month)
Sales ($1,000 per Month 1 A 2 3 4 5 6 7 8 9 10 11 12 40 46 49 58 76 B C D E F 61 73

17. Measuring the Slope of a Curve1 A 2 3 4 5 6 7 8 9 40 43 46 49 54 B C D 53 H
Advertising ($1,000 per Month)
Sales ($1,000 per Month
1. The slope of this curve at point B . . .
2. is the slope of the straight line tangent to the curve at point B.
3. Along the tangent line, when advertising increases from 0 to 3 units (ΔX = 3)
4. sales increase from 43 to 49 units (ΔY= 6). So the curve's slope at point B is = 6/3 = 2.

18. Straight Lines with Different Slopes and Vertical InterceptsY X a
b > 0
b < 0
b = 0
(a)

19. Straight Lines with Different Slopes and Vertical InterceptsY X
a < 0
a = 0
a > 0
(b)

20. Shifts in the Graph of Advertising and Sales
Advertising ($1,000 per Month)
Sales ($1,000 per Month
July 64 C'
June 58 C
September
C'' 6

21. Shifts of Curved Lines and Straight LinesY X C
(a) C'
An increase in Z causes an increase in Y at any value of X