Basic Economic Concepts and the Market Mechanism
What this domain tests
The basic-concepts domain examines whether you can use scarcity, choice and opportunity cost to explain real decisions, and whether you can apply demand, supply, elasticity and price controls to market outcomes. MATSEC questions often ask you to distinguish a shift from a movement along a curve and to interpret diagrams in words.
Core rules
- Scarcity forces choice; opportunity cost is the value of the next-best alternative forgone, not the sum of all alternatives.
- A PPF shows efficient combinations; points inside are inefficient, outside are unattainable with current resources and technology.
- Demand is a relationship between price and quantity demanded, ceteris paribus. A price change moves along the curve; a change in income, tastes, substitutes, complements or expectations shifts it.
- Supply shifts with input costs, technology, taxes/subsidies and number of firms.
- Equilibrium occurs where Qd = Qs. A binding price ceiling below equilibrium creates shortage; a binding price floor above equilibrium creates surplus.
- Elasticity measures responsiveness. If |PED| < 1, demand is inelastic and a price rise increases total revenue.
Worked example
Qd = 100 − 2P; Qs = 20 + 2P. Set equal: 100 − 2P = 20 + 2P, so 80 = 4P, P = €20 and Q = 60. A ceiling at €15 is binding: Qd = 100 − 30 = 70; Qs = 20 + 30 = 50; shortage = 20 units. The price cannot rise to clear the market, so rationing or queues appear.
Traps
Do not say a price change shifts demand. Do not confuse a shortage with a fall in demand. In elasticity, use the midpoint formula when asked, and remember revenue = P × Q. Always state ceteris paribus and check whether a control is binding.