Economics as a Science
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Economists use scientific methods to understand economic phenomena.
They develop theories, collect and analyze data, and test their hypotheses.
The scientific method helps them verify or refute their ideas.
Scientific Method in Economics
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Economists take a systematic approach to understanding the economy.
They use observation, theory, and experimentation (though direct experiments are often
impractical).
Instead, they rely on "natural experiments" provided by history.
Role of Assumptions
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Assumptions simplify complex economic systems, making them easier to study.
Different assumptions are used for different questions and to analyze short-term vs. longterm effects.
Economic Models
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Economists use diagrams and equations to represent reality while omitting unnecessary
details.
Models help highlight important factors and improve our understanding of economic
concepts.
Circular-Flow Diagram
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A visual representation of the economy, showing how money flows between households
and firms.
It highlights two key economic decision-makers (households and firms) and two types of
markets (for goods/services and for factors of production like labor and capital).
Circular-Flow Diagram (Figure 1)
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A visual representation of how money, goods, and services move through the economy.
It shows the interaction between two key economic agents:
o Firms: Produce goods/services and use factors of production.
o Households: Own factors of production (labor, land, capital) and consume
goods/services.
It highlights two types of markets:
o Markets for Goods and Services: Firms sell, households buy.
o Markets for Factors of Production: Households sell (labor, land, capital), firms
buy.
Firms and Households in Markets
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Markets for Goods and Services: Firms act as sellers, and households act as buyers.
Markets for Factors of Production: Households supply labor and other resources, while
firms purchase these inputs.
Production Possibilities Frontier (PPF)
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A graph that shows the different combinations of goods/services an economy can
produce given:
o Available resources (factors of production).
o Technology.
It illustrates trade-offs, opportunity costs, and efficiency in production.
Production Possibilities Frontier (PPF) - Figure 2
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A graph that shows the maximum combinations of two goods (e.g., cars and computers)
that an economy can produce with its available resources.
Illustrates trade-offs: Producing more of one good requires producing less of another.
Efficient Levels of Production
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When an economy is fully utilizing its resources, it operates on the PPF.
Moving along the curve involves trade-offs.
o Example: Moving from point A to B means sacrificing 200 computers to produce
100 more cars.
Inefficient Levels of Production
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Points inside the PPF indicate underutilized resources (e.g., unemployment, inefficiency).
These points represent potential production that is not being achieved.
Opportunity Cost
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The cost of producing one good in terms of the amount of another good that must be
sacrificed.
Represented by the slope of the PPF.
Bowed-Outward Shape of the PPF
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The PPF is typically concave (bowed outward) due to resource specialization.
Opportunity cost of producing cars is higher when producing many cars and fewer
computers.
Opportunity cost of producing cars is lower when producing fewer cars and more
computers.
Technological Advance
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Shifts the PPF outward, allowing more production of both goods.
Leads to economic growth, increasing potential output.
Technological Advance and PPF Shift
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A technological improvement (e.g., in computer production) allows more output with
the same resources.
This shifts the PPF outward, increasing the economy’s ability to produce both goods.
Example: Moving from point A to G shows higher production of both cars and
computers.
Microeconomics vs. Macroeconomics
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Microeconomics: Focuses on how households and firms make decisions and interact in
markets.
Macroeconomics: Studies economy-wide phenomena such as inflation, unemployment,
and economic growth.
The Economist as a Policy Adviser
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Economists analyze economic issues using two types of statements:
o Positive Statements (Descriptive): Explain the world as it is and can be tested
with evidence.
▪ Example: "Minimum-wage laws cause unemployment."
o Normative Statements (Prescriptive): Suggest how the world should be, based
on values or opinions.
▪ Example: "The government should raise the minimum wage."
Graphing in Economics (Appendix)
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Purpose of Graphs:
o Help visualize economic relationships that might be complex in words or
equations.
o Make it easier to spot trends and patterns.
Types of Graphs:
o Pie Chart: Shows proportions.
o Bar Graph: Compares categories.
o Time-Series Graph: Displays data over time.
Table A-1: Novels Purchased by Emma
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Shows how many novels Emma buys at different prices and income levels.
The higher Emma's income, the more novels she purchases at each price.
This data is used to draw demand curves (D₀, D₁, D₂) in Figures A-3 and A-4.
Graphing Review (Appendix)
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Negatively Related Variables:
o When one variable increases, the other decreases.
o Example: Price vs. Quantity Demanded (demand curves are downwardsloping).
Positively Related Variables:
o When one variable increases, the other also increases.
o Example: Income vs. Quantity Demanded for normal goods.
Movement vs. Shift in a Curve:
o Movement along the curve: Caused by a price change.
o Shift in the curve: Caused by non-price factors (like income changes).
Figure A-3: Demand Curve
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D₀ represents Emma’s demand for novels at an income of $40,000.
Price and quantity demanded are negatively related, so the curve slopes downward.
Example:
o At $5 per novel, Emma buys 10 novels.
o At $9 per novel, she buys 3 novels.
Figure A-4: Shifting Demand Curves
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Demand increases (shifts right to D₂) if Emma’s income rises to $50,000.
Demand decreases (shifts left to D₀) if her income falls to $30,000.
Higher income means Emma buys more novels at any price.
This shift illustrates how income affects demand, assuming novels are a normal good.