Basic Economic Concepts
What this domain tests
Basic Economic Concepts covers scarcity, opportunity cost, marginal reasoning, production possibilities, comparative advantage and trade, and the positive/normative distinction. CLEP questions are often definitional but test application: compute opportunity costs correctly and apply the right decision rule.
Core rules
- Scarcity forces choice; every choice has an opportunity cost - the value of the next-best alternative, including implicit costs such as forgone salary or forgone interest.
- Marginal analysis: act if marginal benefit exceeds marginal cost; stop where MB = MC. Sunk costs never affect the decision.
- Positive statements are testable claims about what is; normative statements are value judgments about what ought to be.
- A PPF shows maximum combinations of two goods. Points inside are inefficient; points outside are unattainable. The curve bows outward because resources are not equally suited to both goods, so opportunity cost rises along the curve. New resources or technology shift it outward.
- Absolute advantage means producing more with the same resources. Comparative advantage means a lower opportunity cost. Trade gains come from comparative advantage, not absolute advantage.
Worked example
Alpha uses one worker-day to make 10 wheat or 5 cloth; Beta uses one worker-day to make 4 wheat or 4 cloth. Alpha's opportunity cost of 1 cloth is 2 wheat; Beta's is 1 wheat. Alpha therefore has comparative advantage in wheat (0.5 cloth per wheat versus Beta's 1 cloth), and Beta has comparative advantage in cloth. Terms of trade must lie between 0.5 and 1 cloth per wheat. If they trade 1 wheat for 0.75 cloth, Alpha gains 0.25 cloth per wheat compared with making cloth itself, and Beta pays 0.75 cloth for wheat instead of 1 cloth. Both gain.
Traps that cost marks
- Choosing the country with absolute advantage instead of comparative advantage.
- Treating a sunk cost as relevant to a current decision.
- Calling a statement normative merely because it contains a number.
- Assuming a straight-line PPF when the question states increasing opportunity cost.
- Forgetting that a mutually beneficial trade price must fall strictly between the two opportunity costs.