ECON1101: Microeconomics
University of New South Wales
1 Thinking as an Economist
Economics โ Study of choices under conditions of
scarcity โ how theyโre made and their results
Micro -Individual consumers and firms; Macro -
Aggregate economy
Cost benefit principle โ Take action if benefit >
cost
Economic surplus โBenefit - cost
Scarcity principle โ having more of one good
means having less of another
Opportunity cost โ Cost of not taking the next
best option
Pitfalls: 1. Absolute amounts vs proportions 2.
Ignoring opportunity costs 3. Sunk costs 4. Average
vs marginal costs and benefits
2 Comparative Advantage: the Basis for
Trade
Absolute advantage โCan perform task with less
resources
Comparative Advantage โ Can perform task with
lower opportunity cost
Specialisation according to comparative advantage
and trade gives maximum output
PPC โ Downward sloping because of scarcity, bow
shaped for a many person economy because of low
hanging fruit, shifts due to economic growth,
population growth, new resources and better
technology
3Supply and Demand
Market - Where buyers and sellers can facilitate
exchange of goods
Demand curve โ downward sloping because of
substitution effect, income effect and reservation
prices
Supply curve โ upward sloping because of low
hanging fruit and rising opportunity costs
Equilibrium โ System at
rest, nobody wants to
change behaviour
Demand shifts right due
to drop in price of
complement, rise in price
of substitute, increased
preference by buyers,
increased population of
buyers and expectation of future higher prices (and
vice versa)
Supply shifts right due to decrease in costs of
productive factors, improvement in technology,
increase in number of suppliers and expectation of
lower prices (and vice versa)
Demand shifts right โ equilibrium price and
quantity both rise
Supply shifts right โ equilibrium price goes down,
quantity goes up
4 Elasticity
Price elasticity of demand/supply -% change
in Q demanded/supplied for 1% change in P
๎โ /
โ / =โ
โร = 1ร
๎๎๎ ๎๎: Inelastic, ๎๎๎
๎๎: Unit elastic, ๎๎๎ ๎๎: Elastic, ๎
๎
๎๎: Perfectly inelastic, ๎๎๎
๎๎๎๎๎๎๎๎๎: Perfectly elastic
Elasticity of demand affected by โ Substitutes,
budget share
Elasticity of supply affected by โNumber of
producers, mobility of inputs, production period
length
Elasticity of demand is โ1at mid-point of
demand curve, <1 to left, >1 to right
Cross price elasticity of demand - % change in
Q demanded for %1 change in price of DIFFERENT
good.
Complement - < 0, Substitute - > 0
5Perfect Competition
Law of demand โ Quantity demanded goes down
as price goes up and vice versa
Need - something that you cannot live without, e.g.
food and water
